By Topic

Journal of Applied Physics

Issue 3 • Date Feb 1996

Filter Results

Displaying Results 1 - 25 of 93
  • Issue Table of Contents

    Page(s): toc1
    Save to Project icon | PDF file iconPDF (89 KB)  
    Freely Available from IEEE
  • Entropy generation minimization: The new thermodynamics of finite‐size devices and finite‐time processes

    Page(s): 1191 - 1218
    Save to Project icon | PDF file iconPDF (501 KB)  

    Entropy generation minimization (finite time thermodynamics, or thermodynamic optimization) is the method that combines into simple models the most basic concepts of heat transfer, fluid mechanics, and thermodynamics. These simple models are used in the optimization of real (irreversible) devices and processes, subject to finite‐size and finite‐time constraints. The review traces the development and adoption of the method in several sectors of mainstream thermal engineering and science: cryogenics, heat transfer, education, storage systems, solar power plants, nuclear and fossil power plants, and refrigerators. Emphasis is placed on the fundamental and technological importance of the optimization method and its results, the pedagogical merits of the method, and the chronological development of the field. © 1996 American Institute of Physics. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Study of shear force as a distance regulation mechanism for scanning near‐field optical microscopy

    Page(s): 1219 - 1223
    Save to Project icon | PDF file iconPDF (424 KB)  

    Results of the investigation into the suitability of the shear‐force distance regulation mechanism for scanning near‐field optical microscopy (SNOM) are presented. It is shown that there is a range of relative sizes of surface features to tip size that gives rise to malfunctions of the shear‐force distance regulation mechanism. If the size of the tip is comparable to the size of any depressions on the sample, the corresponding shear‐force image may show contrast reversal. It is also shown that the resolution obtained when imaging a surface with the shear‐force scanning microscope may differ for the two perpendicular lateral directions. The resolution along the oscillation axis is usually lower than the one perpendicular to it. This has implications for SNOM images. Therefore, the interpretation of shear force, and hence SNOM images, may become complex when imaging any sample with significant surface roughness. © 1996 American Institute of Physics. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Stress sensitivity of electromagnetic resonances in circular dielectric disks

    Page(s): 1224 - 1232
    Save to Project icon | PDF file iconPDF (183 KB)  

    A formula for predicting the stress effect on the electromagnetic resonances of dielectric resonators is obtained by applying a perturbation method to the three‐dimensional Maxwell’s equations in which the dielectric permittivity tensor is perturbed by the applied stress (or strain) field through the piezo‐optic effect. The dielectric resonator, which is surrounded by infinite free space, can be isotropic or anisotropic and of arbitrary shape. By using previously obtained two‐dimensional closed‐form solutions as the approximate unperturbed solutions, stress effect on the electromagnetic resonances in a dielectric circular disk is studied. Frequency changes of both the transverse electric and transverse magnetic modes are computed for disks of gallium arsenide and under three cases of loading: (1) a pair of diametral forces, (2) steady vertical acceleration, and (3) steady horizontal acceleration. In the latter two cases, the bottom face of the disk is supported by a rigid base. © 1996 American Institute of Physics. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Metalorganic molecular beam epitaxy of strain‐compensated InAsP/InGaAsP multi‐quantum‐well lasers

    Page(s): 1233 - 1237
    Save to Project icon | PDF file iconPDF (595 KB)  

    Strain‐compensated InAsP/InGaAsP multi‐quantum‐wells (MQWs) grown by metalorganic molecular beam epitaxy (MOMBE) are characterized by conventional photoluminescence (PL), micro‐PL, transmission electron microscopy, and x‐ray diffraction measurements and applied to fabricate 1.3 μm wavelength laser diodes. These methods reveal that there is no deterioration in the optical properties or structure of strain‐compensated MQWs having up to 25 wells, which means that the critical thickness of InAsP grown by MOMBE exceeds 1000 Å. The critical conditions of strain and thickness over which misfit dislocations are generated are determined for the MQWs. The MQW lasers with ten wells (Lz=55 Å) have no misfit dislocations and have uniform threshold current densities of 0.9±0.1 kA/cm2. The maximum operating temperature Tmax of the lasers increases with increasing well number, the highest Tmax is 155 °C, which is obtained for MQW lasers with 15 wells. The lasers have no problems in terms of long‐term reliability. © 1996 American Institute of Physics. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Gain switching of an erbium‐doped silica‐based planar waveguide laser

    Page(s): 1238 - 1243
    Save to Project icon | PDF file iconPDF (137 KB)  

    The gain switching of an erbium‐doped waveguide laser is investigated both theoretically and experimentally. We analyze the lasing characteristics of gain‐switched laser based on coupled rate equations, taking ground state absorption and the saturation effect into account. The analyzed theory indicates that the repetition rate, pulse width, and peak power vary when the pump conditions are changed. Gain‐switched optical pulses are experimentally generated in the erbium‐doped waveguide laser with intensity modulated optical pumping at 651 nm using a dye laser and an acousto‐optic modulator. The pulses are controlled with widths of 660–2600 ns and peak powers of 1.0–6.5 mW at repetition rates of 18–60 kHz by changing the average pump rate between 2.0 and 7.0. These experimental results agree with theoretical calculations of the pulse width, peak power, and repetition rate against the pump rate. © 1996 American Institute of Physics. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Optical nonlinearities of Au/SiO2 composite thin films prepared by a sputtering method

    Page(s): 1244 - 1249
    Save to Project icon | PDF file iconPDF (587 KB)  

    Third‐order nonlinear optical properties of Au/SiO2 composite thin films have been investigated by means of a degenerate four‐wave mixing at room temperature. In the optical‐absorption spectra the absorption peak due to the surface plasmon resonance of Au particles is observed at the wavelength around 530 nm. With increasing the mean diameter of Au particles, the absorption at the peak is increased and the full width at half‐maximum of the absorption band is decreased from 130 to 80 nm. The third‐order nonlinear susceptibility χ(3) exhibits a peak at the wavelength of the absorption peak and the maximum value of χ(3) is obtained to be 2.0×10-7 esu. The size‐dependent enhancement of the χ(3) in Au particles with the mean diameter of 3.0–33.7 nm has been also investigated. The value of χ(3)/α (α: absorption coefficient) for the films is increased upon an increase of mean diameter of Au particles. This is explained by the size dependences of the local‐field factor and the imaginary part of dielectric constant of the metal particles. © 1996 American Institute of Physics. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Effect of Knudsen‐layer formation on the initial expansion and angular distribution of a laser‐produced copper plasma at reduced pressure of air

    Page(s): 1250 - 1257
    Save to Project icon | PDF file iconPDF (171 KB)  

    The initial expansion of a copper plasma generated at reduced pressure (20 mTorr air) by XeCl excimer laser irradiation of 308 nm has been studied by fast intensified charge‐coupled device photography of the overall visible plume emission with a time resolution of 3 ns. The spatial distribution and its temporal development along the target normal as well as in a plane parallel to the sample surface were measured in a single laser shot (28 ns). We report the first in situ measurement and observation of a one‐dimensional plasma expansion with very small divergence during the initial stage (δt≪150 ns) at reduced pressure for low laser fluence (5.4 J cm-2). The related angular distribution of ablated particles has a cosn Θ form where n≳36 for δt≤150 ns and Θ≪20°. The observed effect corresponds to a highly collisional plasma, where strongest forward peaking beyond the Knudsen‐layer edge takes place. For times greater than 150 ns, the plasma switches into a three‐dimensional expansion corresponding to an effusion model with recondensation. A nearly constant center‐of‐mass velocity in the range of 6×103 m s-1 has been observed. A particle velocity at the surface of uk=2×103 m s-1, in good agreement with the theory of unsteady adiabatic expansion, has been confirmed through a measured excitation temperature of T≊104 K revealing an image of the kinetic energy. © 1996 American Institute of Physics. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Upconversion in Er‐implanted Al2O3 waveguides

    Page(s): 1258 - 1266
    Save to Project icon | PDF file iconPDF (190 KB)  

    When pumped with a 1.48 μm laser diode, Er‐implanted Al2O3 ridge waveguides emit a broad spectrum consisting of several distinct peaks having wavelengths ranging from the midinfrared (1.53 μm) to the visible (520 nm). In order to explain these observations, three different upconversion mechanisms are considered: cooperative upconversion, excited state absorption, and pair‐induced quenching. It is found that for samples with a high Er concentration (1.4 at. %), cooperative upconversion completely dominates the deexcitation of the Er3+ ions. For a much lower concentration (0.12 at. %), the influence of cooperative upconversion is strongly reduced, and another upconversion effect becomes apparent: excited state absorption. These conclusions are based on measurements of the luminescence emission versus pump intensity, and also on measured luminescence decay curves. The upconversion coefficient is found to be (4±1)×10-18 cm3/s; the excited state absorption cross section is (0.9±0.3)×10-21 cm2. It is shown that in spite of these upconversion effects, a high fraction of the Er3+ can be excited at low pump powers. For pump powers between 2 and 10 mW, the optimum Er concentration is calculated. The results show that for an Er concentration of 0.5 at. %, more than 2 dB/cm net optical gain is achievable at a pump power less than 10 mW. © 1996 American Institute of Physics. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Quadratic electro‐absorption and electro‐optic effects in a guest/host nonlinear optical polymeric system

    Page(s): 1267 - 1274
    Save to Project icon | PDF file iconPDF (148 KB)  

    Quadratic electro‐absorption (QEA) and quadratic electro‐optic measurements were performed with a guest/host system consisting of 4(4’‐N,N‐Dimethylaminophenyl)‐1,1‐bis(trifluoromethyl sulfonyl)‐1,3‐butadiene doped in poly(ethyl)methacrylate host polymer. The imaginary part of the QEA response was measured over a wavelength range of 450–600 nm. The real and imaginary parts of the electric field induced optical Kerr coefficient were measured at wavelengths near and far from resonance. Under different polarizations of the optical field in the QEA measurement, the two contributing coefficients of the third order susceptibility (χ(3)) were deduced. A distinctive temperature variation of the third order response was observed. Temperature dependence measurements from ambient to well above the glass transition of the guest‐host system were carried out. The same chromophore in a different polymer host, poly(vinyl)chloride, was also investigated. Correct expressions for the real and imaginary parts of the Kerr coefficient are provided. The present results confirm the importance of the electronic contribution to χ(3) at room temperature where molecular reorientation is insignificant. At high temperatures (above the glass transition temperature of the polymer) the ratio of χ(3)3333(3)1133 deviates from -2, which is predicted by the elastic model assuming molecular reorientation to be the dominant mechanism. © 1996 American Institute of Physics. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Fluttering fountains: Annular geometry

    Page(s): 1275 - 1278
    Save to Project icon | PDF file iconPDF (239 KB)  

    Under certain conditions of flow rate, height, and feedback, periodic or chaotic fluttering oscillations can be observed as the sheet of water from a dam or waterfall fountain descends through the air. Numerical and analytical interpretations of this phenomenon have recently been reported. The extension of these results to other fountain geometries is discussed here together with experimental observations on an annular waterfall fountain. © 1996 American Institute of Physics. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Role of sputtered Cu atoms and ions in a direct current glow discharge: Combined fluid and Monte Carlo model

    Page(s): 1279 - 1286
    Save to Project icon | PDF file iconPDF (152 KB)  

    The Cu atoms sputtered from the cathode and the corresponding Cu ions in an argon direct current glow discharge are described by a combination of two models: a fluid model for their overall behavior (diffusion and migration) in the entire discharge and a Monte Carlo model for the explicit transport of the Cu ions in the cathode dark space. The models are combined with other models described previously for the electrons, Ar ions, fast Ar atoms, and Ar metastables, in order to obtain an overall picture of the glow discharge. Results of the fluid model are the densities and fluxes of the Cu atoms and ions. At 100 Pa and 1000 V the Cu atom and ion densities are of the order of 1012–1013 and 1010–1011 cm-3, respectively. The ionization degree is hence about 1%, which is much higher than for Ar. The Cu ion to Ar ion density is about 6% and the Cu ion to Ar ion flux is about 5%. The energy distribution of the Cu ions bombarding the cathode is calculated with the Monte Carlo model and shows good agreement with experiment. It is characterized by a peak at maximum energy, in contrast to the energy distribution of Ar ions and fast atoms. Since sputtering increases with the bombarding energy, the amount of self‐sputtering is significant, although still clearly lower than the contribution of Ar ions and fast atoms. The influence of pressure, voltage, and current on all these quantities is investigated. © 1996 American Institute of Physics. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Ion energy and plasma characterization in a silicon filtered cathodic vacuum arc

    Page(s): 1287 - 1291
    Save to Project icon | PDF file iconPDF (88 KB)  

    The plasma generated by a silicon filtered cathodic vacuum arc has been investigated using a Faraday cup and Langmuir probes. Ion energy distributions for arc currents ranging from 30 to 80 A were measured. Mean ion energies were found to range from 8 to 18 eV. The ion saturation current density varied from 0.1 to 1 mA/cm2 depending on both the arc and filter coil currents. The energy distributions were fitted by a sum of Gaussians spaced according to the gas dynamic model for ion acceleration at the cathode spot. © 1996 American Institute of Physics. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Downstream ion drift in an electron cyclotron resonance plasma process

    Page(s): 1292 - 1297
    Save to Project icon | PDF file iconPDF (157 KB)  

    The collisionless two‐fluid model of a plasma is applied to the drift of ions and electrons downstream from an electron cyclotron resonance source. A plasma potential drop of 20 V is found for the system parameters typical of plasma‐assisted epitaxy of the group III nitrides. This model provides a simple way to design downstream magnet coils to tune the ion acceleration, a key parameter in growth and etching processes. Compared to previous analyses, the present work makes clear the conditions under which an ion accelerating potential actually appears, in terms of the expansion that the plasma undergoes upon exiting from the source region. Published measurements of the potential profile downstream from a N2 plasma source can be fit assuming an electron temperature kTe=3.2 eV, somewhat greater than half the excitation energy of the long‐lived A 3Σ+u metastable state. The analysis is consistent with the plane probe current–voltage characteristics obtained from the growth stage in a plasma‐assisted molecular‐beam epitaxy process. For a 10 W plasma used in the growth of GaN, the value of ion saturation current implies a plasma density at the source of 1010 cm-3. Considering the suppression of electron current by the magnetic field, the measured ratio of ion to electron saturation current implies an electron temperature of 3.8 eV. © 1996 American Institute of Physics. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Plasma properties determined with induction loop probes in a planar inductively coupled plasma source

    Page(s): 1298 - 1302
    Save to Project icon | PDF file iconPDF (150 KB)  

    Electromagnetic fields in a planar rf inductively coupled plasma source, of interest for materials processing, were measured using a two‐loop inductive (B‐dot) probe. The two loops were oriented to measure the time derivative of the axial and radial components of the magnetic field B˙z and B˙r, respectively, at various positions in the r–z plane of the cylindrically symmetric argon discharge. Maxwell’s equations were used with this data to calculate amplitudes of the rf azimuthal electric field Eϕ and current density Jϕ, as well as the complex permittivity ϵ of the plasma, from which the electron density ne was calculated. The electron densities calculated using this technique were found to compare favorably to the results of measurements made with Langmuir probes. Electron drift velocities calculated from Jϕ and ne were found to be comparable to electron thermal velocities in the region of highest Eϕ and thus may contribute to local enhancement of electron impact reactions, thereby affecting process chemistry and uniformity. The peak in the drift velocity moved radially outward as the pressure increased due changes in the radial plasma density profile. This technique is applicable to chemistries where Langmuir probes are not practical. © 1996 American Institute of Physics. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Dusty plasma formation: Physics and critical phenomena. Theoretical approach

    Page(s): 1303 - 1314
    Save to Project icon | PDF file iconPDF (220 KB)  

    Kinetics of the many‐stage process of particle nucleation and growth in low‐pressure rf discharge in silane SiH4–Ar is considered. The particle growth is considered in an analytical model as a chain of negative‐ion molecular reactions, stimulated by vibrational excitation. In the framework of this model, a limitation of first generation particle size is explained as well as the strong temperature effect on cluster growth. A theory of critical phenomena of cluster trapping in discharge area has been elaborated to describe the neutral particle selection by size, and the particle concentration increases during a period exceeding the residence time in plasma. Finally, an analytical model of critical phenomena of particle coagulation and its influence on plasma parameters is developed to explain the latest experimental results on supersmall 2–10 nm cluster kinetics. All theoretical results are presented in comparison with corresponding new experimental data and with results of an especially made computer simulation. © 1996 American Institute of Physics. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The transformation structure of zirconia‐alumina nanolaminates studied by high resolution electron microscopy

    Page(s): 1315 - 1319
    Save to Project icon | PDF file iconPDF (432 KB)  

    Quantitative high resolution electron microscopy (HREM) was employed to study the crystallography of a zirconia‐alumina transformation‐toughening nanolaminate. The nanolaminate consisted of alternating layers of polycrystalline zirconia and amorphous alumina. The zirconia layer thickness was scaled to insure unity volume fraction of the metastable tetragonal phase at the growth temperature, as predicted by an end‐point thermodynamics model and verified by x‐ray diffraction. In the microscopy sample, phase identification was achieved from precise measurements of lattice spacings using digital diffractograms of individual nanocrystallites. Of the nanocrystallites analyzed, (22±6)% were monoclinic in a distinct crystallographic relationship with their tetragonal neighbors. The following plane and direction relationships were identified: m(100)//t(100) and m[001]//t[001]. The observed structure is the result of a stress‐induced transformation from the tetragonal phase. This transformation was localized to nanosized regions within the individual zirconia layers. © 1996 American Institute of Physics. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Influence of ion irradiation damage on properties of porous silicon

    Page(s): 1320 - 1323
    Save to Project icon | PDF file iconPDF (425 KB)  

    We have studied the effect of ion‐irradiation on porous Si formation, microstructure, and optical properties. Porous Si was first self‐implanted and then fabricated by anodization. With increasing implantation dose, the photoluminescence (PL) intensity decreased, and the PL spectra were also red shifted. Porous Si formed from crystal Si emitted light, while that from preamorphized Si did not. Porous Si luminescent patterns with a resolution of 2 μm features were formed by selective ion implantation. © 1996 American Institute of Physics. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On the structural properties of a‐Si1-xCx:H thin films

    Page(s): 1324 - 1329
    Save to Project icon | PDF file iconPDF (141 KB)  

    The structural and chemical properties of hydrogenated amorphous silicon carbide (a‐Si1-xCx:H) thin films, deposited by plasma‐enhanced chemical‐vapor deposition, were determined by extended x‐ray absorption fine structure (EXAFS), x‐ray‐absorption near‐edge spectroscopy (XANES), small‐angle x‐ray scattering, Fourier transform infrared (FTIR) spectroscopy, Auger electron spectroscopy, and visible spectrometry. The EXAFS and XANES results show the crucial influence of the ‘‘starving’’ plasma deposition conditions on the structural properties of wide‐gap a‐Si1-xCx:H films and are consistent with the FTIR and optical‐absorption data. The first‐neighbors distance for alloys with smaller carbon content or deposited at higher silane flow are very close to the mean Si–Si distance obtained for a‐Si:H. On the other hand, the EXAFS spectra of films with higher carbon content (x≳50 at. %) and deposited under ‘‘starving’’ plasma regime show Si–C distances similar to crystalline SiC (c‐SiC). The presence of a typical c‐SiC resonance in the XANES spectra of the same samples is evidence that the material has a chemical order close to that of c‐SiC. © 1996 American Institute of Physics. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Neutron diffraction analysis of Nd3Fe29-xTx (T=Ti, Cr, Mn)

    Page(s): 1330 - 1336
    Save to Project icon | PDF file iconPDF (138 KB)  

    Rietveld analysis of neutron‐diffraction data from Nd3Fe29-xTx (T=Ti, Cr, and Mn) has been used to determine the location of the substitutional atoms and the magnetic moments. Reanalysis of the T=Ti data confirms that the space group A2/m is a better choice than P21/c, which had previously been used to describe the structure. The Ti atom locations and concentrations remain unaffected in the two space groups, but for the other substituents the refined concentrations are well behaved in A2/m, whereas in P21/c the refinements were unstable due to the symmetry relations between certain substituted sites. The site occupancies are analyzed in terms of steric and environment effects. A possible explanation for the high Curie temperature of the Cr compound is proposed. © 1996 American Institute of Physics. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Interaction of copper with cavities in silicon

    Page(s): 1337 - 1350
    Save to Project icon | PDF file iconPDF (1096 KB)  

    Copper in Si was shown to be strongly bound at cavities formed by He ion implantation and annealing. Evolution of this system during heating was observed by Rutherford backscattering spectrometry and transmission electron microscopy. Results were mathematically modeled to characterize quantitatively the binding of Cu in the cavities and, for comparison, in precipitates of the equilibrium silicide, η‐Cu3Si. Binding of Cu to cavities occurred by chemisorption on the walls, and the binding energy was determined to be 2.2±0.2 eV relative to solution in Si. The heat of solution from the silicide was found to be 1.7 eV, consistent with the published phase diagram. These findings suggest the use of cavities for metal‐impurity gettering in Si devices. Hydrogen in solution in equilibrium with external H2 gas displaced Cu atoms from cavity walls, a mechanistically illuminating effect that is also of practical concern for gettering applications. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The correlation of dimensionality with emitted wavelength and ordering of freshly produced porous silicon

    Page(s): 1351 - 1356
    Save to Project icon | PDF file iconPDF (111 KB)  

    Freshly produced red, yellow and green emitting porous Si specimens have been studied by NEXAFS and EXAFS (near edge and extended x‐ray absorption fine structure). The emission peaks are at 690, 580, and 520 nm, which almost covers the full visible range that direct anodization can achieve. The correlation between the co‐ordination numbers of the first, second and third Si neighbor shells from Fourier transform fitting of EXAFS and both emission peak energies and optical band gaps estimated by PLE (photoluminescence excitation dependence) suggests that the nanostructures of the PS are nanowires, rather than nanocrystalline. Two types of quantum nanowire with one and one‐plus‐a‐fraction dimensionality are proposed to interpret the correlation. The order factors of the theoretical fits suggest the nanowires of the freshly produced PS have crystalline cores. © 1996 American Institute of Physics. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Growth of {100} textured diamond films by the addition of nitrogen

    Page(s): 1357 - 1364
    Save to Project icon | PDF file iconPDF (737 KB)  

    Localized {100} fiber textured diamond films were grown by addition of 20–200 ppm nitrogen into the gas phase during hot‐filament chemical‐vapor deposition (CVD). Cathodoluminescence indicates the presence of the nitrogen‐vacancy system in the {100} textured diamond, whereas a blue ‘‘band A’’ luminescence is normally observed in diamond films grown without nitrogen addition. The results demonstrate that the nature of the substrates used for growth has no appreciable influence on the {100} texture, which implies that this fiber texture is obtained by competitive growth and selection of facets. The interaction of nitrogen with the {100} surface is a highly important factor in this process. Homoepitaxial growth shows that the addition of a small amount of nitrogen greatly enhances the growth rate of the {100} faces, making 〈100〉 the fastest growth direction in comparison with the 〈110〉 and 〈111〉 directions. This is attributed to breaking of a part of the dimers on the (2×1) reconstructed {100} surface by nitrogen compounds. The {100} texture in narrow, ring‐shaped areas on diamond layers grown by the flame technique can also be attributed to the occurrence of a certain amount of nitrogen in the gas phase. It is demonstrated that the flame grown polycrystalline diamond layers have morphologies and cathodoluminescence features that are consistent with those observed in the hot‐filament CVD diamond films grown with the addition of nitrogen. © 1996 American Institute of Physics. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • p‐type ion‐implantation doping of Al0.75Ga0.25Sb with Be, C, Mg, and Zn

    Page(s): 1365 - 1370
    Save to Project icon | PDF file iconPDF (142 KB)  

    p‐type ion‐implantation doping of Al0.75Ga0.25Sb is reported. The surface morphology and electrical properties of Al0.75Ga0.25Sb are shown by atomic force microscopy and Hall measurements to be degraded after rapid thermal annealing of 650 °C. Implantation of Be and Mg results in sheet hole concentrations twice that of the implanted acceptor dose of 1×1013 cm-2 following a 600 °C anneal. This is explained in terms of double acceptor or antisite defect formation. Implanted C acts as an acceptor but also demonstrates excess hole conduction attributed to implantation‐induced defects. Implanted Zn requires higher annealing temperatures than Be and Mg to achieve 100% effective activation for a dose of 1×1013 cm-2 probably as a result of more implantation‐induced damage created from the heavier Zn ion. Secondary ion mass spectroscopy of as‐implanted and annealed Be, Mg, and C samples are presented. Diffusion of implanted Be (5×1013 cm-2, 45 keV) is shown to have an inverse dependence on temperature that is attributed to a substitutional‐interstitial diffusion mechanism. Implanted Mg (1×1014 cm-2, 110 keV) shows dramatic redistribution and loss at the surface of up to 56% after a 600 °C anneal. Implanted C (2.5×1014 cm-2, 70 keV) displays no redistribution even after a 650 °C anneal. This work lays the foundation for using ion‐implantation doping in high performance AlGaSb/InGaSb‐based p‐channel field‐effect transistors. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Zinc incorporation into InP grown by atmospheric pressure metalorganic vapor phase epitaxy

    Page(s): 1371 - 1377
    Save to Project icon | PDF file iconPDF (158 KB)  

    Zinc incorporation into InP grown by atmospheric pressure metalorganic vapor phase epitaxy has been studied systematically as a function of Zn source flow rate, substrate orientation, and growth temperature. Within the growth conditions for device quality layers, a Zn saturation level exists which varies with substrate orientation. The incorporation kinetics is analyzed using a surface adsorption‐trapping model. We demonstrate that the Langmuir state of adsorption–desorption process is not established during growth due to the interruption of the surface processes by layer growth. The existence of a saturation level at a given growth condition indicates that Zn atoms incorporate at defect sites instead of the normal growth sites for In. Two parameters are used to characterize the properties of the surface defect, i.e., the capture cross section and the time of desorption for Zn atoms. The implication of these parameters and their substrate orientation and growth temperature dependencies are discussed. © 1996 American Institute of Physics. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

Aims & Scope

Journal of Applied Physics is the American Institute of Physics' (AIP) archival journal for significant new results in applied physics

Full Aims & Scope

Meet Our Editors

Editor
P. James Viccaro
Argonne National Laboratory