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High Speed Semiconductor Devices and Circuits, 1995. Proceedings., IEEE/Cornell Conference on Advanced Concepts in

Date 7-9 Aug 1995

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Displaying Results 1 - 25 of 68
  • Blue-green laser diodes

    Page(s): 2 - 8
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    The current status, as well as some key issues related to the growth and characterization of II-VI blue/green laser diodes are reviewed. The Zn(Se,Te) graded contact to p-ZnSe is effective in supporting the room-temperature CW operation of green (508 nm) laser diodes while device lifetimes are currently limited by the formation of dark defects in the active region. The role of extended and point defects in degradation will be discussed. Additional problems have arisen in the move to shorter wavelengths. For example, an observed increase of resistivity with increased bandgap energy has been associated with the formation of AX centers, a DX like behavior for acceptors View full abstract»

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  • Gate controlled surface tunneling transistor

    Page(s): 490 - 497
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    A three terminal, field effect silicon surface tunneling transistor (STT) is presented. The device incorporates lateral band-to-band tunneling as the current conduction process. This lateral band-to-band tunneling is controlled by the application of a gate bias. Two-dimensional computer simulations and experimental results verify the operation of the device. The drain current is found to vary exponentially with respect to both the drain voltage and gate voltage. The drain current's exponential relationship to the gate voltage may prove useful to signal detector type applications. Temperature dependence characteristics and switching performance for the device are also presented View full abstract»

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  • Design and fabrication of a three terminal quantum storage device

    Page(s): 209 - 218
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    We have a significant new development in our group's resonant tunneling diode memory switching devices that should enhance application in ultra-dense memory and logic. The original device, a double barrier resonant tunneling diode in the GaAs-AlAs materials system has shown multiple conduction states and memory switching in Schrodinger Poisson and Wigner formalism simulations, as well as in laboratory measurements. In new work we have demonstrated this phenomenon for similarly designed triple barrier resonant tunneling devices in Schrodinger Poisson simulations and in the laboratory. Memory switching has not been previously reported in these devices. The triple barrier device is part of our development of a three terminal quantum storage device which we believe will have significantly enhanced switching characteristics. The additional AlAs layer has been used as an etch stop in the fabrication of three terminal devices. A process has been developed using a suscinic acid selective etch to etch down to the top AlAs layer where metal is evaporated directly on the N+ layer forming a Schottky contact View full abstract»

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  • Optimization of 3D-SMODFETs on GaAs and InP substrates with a simple analytical model

    Page(s): 132 - 140
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    Using a simple analytical method followed by a computer program that solves the detailed quantum-mechanics, it is possible to design the optimum material structures for pseudomorphic MODFETs with full channels. Using a MODFET with a pseudomorphic graded channel, and atomic planar doped pseudomorphic barriers on both sides of the channel, it is possible to achieve record-breaking electron sheet densities in the channel without having carriers in the barrier (Double-Doped Double-Strained MODFET, 3D-SMODFET). This theory is used to predicted the optimum material designs (quantum-mechanical solution) for GaAs, InP and GaN based structures View full abstract»

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  • Micromachined optical sensor

    Page(s): 189 - 193
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    We report the fabrication and testing of a surface micromachined optical deformation sensor. The sensing element is a suspended mirror which forms part of a Fabry-Perot interferometer. In the presence of an external force, shift in interference fringe as well as change in power spectral density was observed. The sensor exhibits linear response to external applied force and has resonant frequency of 15 kHz for a symmetric double serpentine springs geometry View full abstract»

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  • P-channel, ion implanted, GaAsSb/InAlAs HIGFETs on InP for digital and microwave applications

    Page(s): 253 - 259
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    We report the first device results of ion implanted, recessed gate, p-channel GaAsSb/InAlAs HIGFETs grown lattice matched to InP with tremendous potential for use in a complementary technology on III-V substrates. The InAlAs/GaAsSb heterostructure possesses excellent hole confinement, and this is coupled to a p-channel device process which employs ion implanted contacts and a recessed gate. This implies the GaAsSb/InAlAs p-channel HIGFET has advantages in both digital and microwave design. Close examination of the GaAsSb/InAlAs heterostructure material during process development, provides an important feedback loop which resulted improved p-channel device characteristics. Microstructural evaluation of the ohmic contacts and its effect on their electrical stability are presented. Direct current characteristics and unique photoelectric characterization results on the fabricated p-channel HIGFETs are provided. Comments on maturing GaAsSb/InAlAs HIGFETs into a self-aligned gate, submicron, complementary technology for integrated circuit applications are outlined View full abstract»

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  • Field control in piezoelectric [111]-oriented InGaAs/GaAs MQW and superlattice devices

    Page(s): 506 - 515
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    In [111]-oriented InGaAs/GaAs multiple quantum wells and superlattices, the field in the wells, barriers, and the average electric field, are deduced using simple analytical expressions. The influence of the design parameters on the conduction-band profile and optoelectronics properties of strained piezoelectric p-i-n diodes is presented. In samples with negative average electric field, transient photocurrent response and photocapacitance-voltage characteristics clearly reveal that carriers accumulate at the extremes of the active region, giving rise to a long-range screening effect of the field in the wells. Coupled quantum wells and piezoelectric superlattices have been studied by photocapacitance techniques, and the revealed features were explained as due to carrier sequential tunneling and accumulation processes View full abstract»

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  • High-performance InGaAs photodetectors on Si and GaAs substrates

    Page(s): 194 - 200
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    In this work, we demonstrate record performance operation of long wavelength (1.55 μm) P-I-N (InP-InGaAs-InP) photodetectors on both Silicon and Gallium Arsenide substrates using a wafer bonding technique. The photodetectors were made by first bonding the P-I-N epitaxial layers to the Si and GaAs substrates followed by chemical removal of the host (InP) substrate from the P-I-N structure. The photodetectors were then fabricated atop the newly exposed P-I-N (InP-InGaAs-InP) epilayers. Dark currents of as low as 57 pA on a GaAs substrate and 0.29 nA on a Si substrate were measured under 5 V reverse bias. The responsivity at 1.55 μm wavelength was measured to be 1 A/W, corresponding to an external quantum efficiency of 80%. The series resistance measured across the bonded interface and P-I-N layers gave 17 Ω on GaAs and 350 Ω on Si, respectively View full abstract»

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  • Dual-gate HFET with closely spaced electrodes on InP

    Page(s): 522 - 531
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    An InGaAs/AlInAs dual-gate HFET with two closely spaced gate electrodes deposited in a common gate recess has been fabricated on InP substrate. The configuration consists of an 0.25 μm RF-driven Γ-gate overlapping to the source and a DC-trapezoid control gate placed approximately 0.2 μm behind the Γ-gate. The fabrication sequence allows one to test the device as a single gate FET before deposition of the second gate. The influence of the second gate on the transistor performance was characterized under DC- and RF-conditions. The device current could be fully modulated by either gate and the small signal RF behaviour could be tested in all modes of operation with the second gate RF-grounded. In comparison with the single gate FET, the dual-gate configuration shows an essentially reduced feedback behaviour with reduced Cdg and Gds however, slightly increased input capacitance Cgs. At Vds=1.2 V f max is enhanced by 40%, from 190 GHz to 260 GHz, whereas the gain-bandwidth product decreases from 90 GHz to 70 GHz. The increase of fmax is strongly drain bias dependent and increases steeply beyond Vds=1.0 V View full abstract»

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  • InP-based 28 GHz integrated antennas for point-to-multipoint distribution

    Page(s): 75 - 84
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    Quasi-optics offers an attractive means of creating moderate-power solid-state millimeter-wave transmitters. This paper presents the development of a 28 GHz oscillator, including an InP power HEMT and integrated with a planar, endfire antenna, which is used in testing metal reflectors designed for generating omni-directional patterns for point-to-multipoint distribution. Results of this work give insight into tailoring the reflectors for omni-directional active arrays View full abstract»

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  • Cascaded self-induced holography: a new fabrication technology for optoelectronics

    Page(s): 388 - 397
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    We present a new method of fabricating submicron gratings with a high filling factor for optoelectronic devices from a glass mask. The glass mask has gratings on both sides with a period of at least four times of the final feature size. By modifying the grating periods on both sides of the glass mask, one can achieve multiple-period gratings with a very fine period spacing for advanced wavelength division multiplexing (WDM) devices. In this paper, we demonstrate 0.5 μm second-order gratings for 1.55 μm distributed feedback (DFB) lasers and gratings with a 6 Å period difference for WDM laser arrays using only optical sources View full abstract»

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  • Monolithic integrated optoelectronic circuits

    Page(s): 357 - 360
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    Monolithic integration of lasers and photodetectors with electronic circuits promises higher bandwidth, improved manufacturability, smaller size, lower power and hence lower costs. This paper reviews the activities of the Fraunhofer IAF on optoelectronic integrated circuits (OEICs) for serial and parallel optical links View full abstract»

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  • Microelectromechanical systems

    Page(s): 9 - 18
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    Integrated circuit technology has brought unprecedented computational power ever closer to the point of use, revolutionizing the design of electronics products and enabling the creation of entirely new product categories. Microelectromechanical systems (MEMS) promise to do the same for electromechanical systems through miniaturization, batch fabrication, and integration with electronics, thereby enabling the development of smart products by providing the required interface between the available computational power and the physical world through the perception and control capabilities of microsensors and microactuators. Micromechanical devices and systems are inherently smaller, lighter, and faster than their macroscopic counterparts, and in many cases are also more precise. MEMS devices are emerging as product differentiators in markets such as automotive, aerospace, industrial process control, electronics instrumentation, office equipment, appliances, and telecommunications. This paper will describe the more commonly employed fabrication techniques of MEMS technology and review several examples of MEMS devices under development at CWRU and elsewhere View full abstract»

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  • Far infrared Ga1-xInxSb/InAs-based strained-layer superlattice detectors grown by OMVPE

    Page(s): 288 - 295
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    Strained-layer, type-II Ga1-xInxSb/InAs superlattice detectors operating at 9 μm have been grown for the first time by OMVPE. In all reported literature thus far, MBE has been exclusively used to grow this particular material system. In the present research, the material was grown by an atmospheric pressure OMVPE reactor using high purity metallorganic precursors (TM Ga, TMSb, TMIn and TBAs). A 300 Å of Ga1-xInxSb buffer layer was grown on n-GaAs(100) substrate followed by 20 periods (60 Å Ga0.6In0.4Sb/60 Å InAs) superlattice. A 300 Å InAs was grown as the capping layer. The growth took place at 600°C with a precracker temperature of 140°C. The absorbance characteristics measured by FTIR showed a shift in the cutoff wavelength λ from 1.8 μm to 2.5 μm when the In mole fraction was varied from 0.1 to 0.4 in Ga1-xIn xSb layer. The use of InAs in Ga0.6In0.4Sb/InAs structures introduces strain and λ shifts from 2.5 μm to 9 μm as confirmed by FTIR. An increase in the number of superlattice periods (from 5 to 20) resulted in an enhanced absorbance edge. p-n photodiodes were fabricated by establishing AuGe/Ni/AuGe contacts on InAs and n-GaAs. The samples were sintered at 430°C for 10 minutes in N2 ambient. The samples were measured to show good I-V and R-V characteristics. The detector was edge-excited using white light to show change in conductance. The measured leakage current (1 mA<at a bias of -0.2 V) and was attributed to the lattice mismatch between GaAs and Ga0.6 In0.4Sb (~8%). A reduction in leakage current (or, improved electrical characteristics) is currently under investigation using a GaSb substrate View full abstract»

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  • Three terminal quantum structure based on resonant interband tunneling

    Page(s): 460 - 464
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    We have demonstrated a three terminal resonant interband tunneling FET (RITFET) and an XNOR device in the hybrid GaSb/AlSb/InAs and InGaAs/GaAlAs material systems. The RITFET achieved the negative transconductance desired in the multifunctional quantum logic devices. The equivalent circuit of the XNOR consists of two enhancement-mode field effect transistors, a resonant tunneling diode, and a load resistor. The XNOR functionality is achieved by using the field effect transistors to control the current through the diode and by the linear-to-multi-on-off input-to-output conversion resulting from the negative differential resistance. DC and timing measurements have confirmed the operations of the device View full abstract»

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  • Efficient I-V simulation of quantum devices using full bandstructure models

    Page(s): 435 - 439
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    For several years it has been recognized that the single band effective mass model is insufficient to simulate quantum transport in material systems which are currently under investigation. This has prompted a growing effort on the part of theorists to include realistic bandstructures in quantum transport simulations. However, full bandstructure current-voltage calculations have proven to be numerically prohibitive. In this work we introduce an efficient technique to calculate current-voltage characteristics for quantum devices using tight-binding bandstructure models View full abstract»

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  • Threshold characteristics of blue to ultraviolet light emitting semiconductor lasers based on the AlGaN material system

    Page(s): 160 - 169
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    Two-dimensional numerical simulations of AlGaN/GaN/AlGaN semiconductor lasers are performed using material parameters obtained from the literature. Important differences between these wide band gap lasers and lasers from other systems are the slow recombination rate and large band discontinuities. The behavior of the threshold, and thus the speed of operation, with variations in the aluminum content of the cladding regions, and the width of the active region are presented. Results for lasing due to band to band recombination and band to impurity level recombination are presented separately. From these we observe that the band to impurity recombination is difficult due to the reduced number of available states for recombination. Stopper layers are investigated and found to be useful at increasing carrier confinement without any detrimental effects because particle tunneling is very strong for majority carriers through the band discontinuities View full abstract»

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  • Current transport in band-gap engineered AlInAs/GaInAs/InP double heterojunction bipolar transistor using chirped superlattice

    Page(s): 552 - 562
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    DHBTs with a new base-collector design are presented. The elimination of the potential barrier at the base-collector junction has been achieved by properly combining the electrostatic potential arising from the ionized dopants in the space charge region and the energy band profile of the CSL. A hot electron launcher structure is utilized to achieve a record combination of breakdown voltage and fT. The effects of CSL parameters on current transport are investigated View full abstract»

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  • Comparison of the load-pull power characteristics of common-emitter and common-base heterojunction bipolar transistors

    Page(s): 243 - 252
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    The power characteristics of common-emitter and common-base AlGaAs-GaAs based HBTs are compared using on-wafer load/pull measurements. Gain compression is more pronounced for common-base HBTs. The sensitivity of the device gain on the load termination conditions is smaller for common-emitter than common-base HBTs. Device self-bias is strongly dependent on load termination at high power levels for CE but not for CB HBTs. As a result, a unique load termination exists resulting in both maximum gain and power added efficiency in the case of CB HBTs. In the case of CE HBTs optimum load terminations can be selected through tradeoffs between the output power and efficiency load-pull contours View full abstract»

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  • Integrated antennas and quasi-optical device arrays

    Page(s): 64 - 74
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    Integrated antennas have been the focus of increasing research activity, particularly for millimeter-wave power combining and “quasi-optical” arrays. This paper reviews some of the work in integrated antennas for oscillator and amplifier arrays carried out at UCSB. This includes unusual phenomena involving coupled-oscillator systems that have led to novel beam scanning concepts for cost-effective mm-wave radar and imaging systems View full abstract»

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  • Performance evaluation of heterojunction bipolar transistors designed for high optical gain

    Page(s): 278 - 287
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    This paper evaluates the performance of thin base Npn heterojunction bipolar transistors designed for high optical gain in the base while biased in the active regime. Pisces/Blaze simulations indicate that injected carrier concentrations exceeding 1019 cm-3 can be achieved resulting in an estimated optical gain ~3000 cm-1. Furthermore, a very large increase in differential base electron concentration with emitter current yields a high modulation depth with no insertion loss but low fT. Estimated performance of this device in a microwave fiber optic link application is given View full abstract»

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  • A ZnS0.07Se0.93 metal-semiconductor field effect transistor

    Page(s): 517 - 521
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    We report the fabrication and test data for a n-ZnS0.07Se0.93 metal-semiconductor field effect transistor (MESFET). A ZnSSe FET could be a key element in opto-electronic integration employing light emitting devices, metal-semiconductor-metal photo-detectors (MSM-PD) and MESFET pre-amplifiers. Wide bandgap n-ZnS0.07Se0.93 is lattice-matched to the GaAs substrate and posses the “light hardness” property. A mesa active island was used to isolate devices. Source and drain (SID) ohmic contacts and gate Schottky contact were formed by Cr/In/Cr and Au, respectively. Recess etching and self-aligning techniques were adopted. Depletion mode FETs with varying gate width-to-length ratio of W/L=200 μm/20 μm, 200 μm/4 μm and 200 μm/2 μm were fabricated and the terminal parameters of a 2 μm FET are as follows: the turn-on voltage, Von≈1.75 V, the pinch-off voltage, VP≈13 V, the unit transconductance, gm=8.73 mS/mm, and the breakdown voltage without a gate-drain bias, BV≈28 V View full abstract»

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  • Vapor phase 6H and 4H SiC epitaxy for high-speed devices

    Page(s): 31 - 39
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    Silicon carbide (SiC), a wide bandgap semiconductor, is currently being developed for enhanced high-power and high-temperature microwave devices. Silicon carbide wafers, now available at up to two-inch diameter with resistivities from 0.02 Ω-cm to 107 Ω-cm, still exhibit features such as micropipes, surface scratches, and inclusions of other polytypes. Vapor phase epitaxy (VPE) of 6H and 4H SiC, typically performed between 1450 and 1600°C using silane and propane reagents, is impacted greatly by the quality of these wafers and the conditions used during in situ etching or the initial stages of growth. By optimizing growth conditions, device-quality homoepitaxial 6H and 4H-SiC has been grown with near specular morphology, background doping levels of less than 1×1014 cm-3, and controlled n- and p-type doping from less than 5×1015 cm-3 to greater than 1×1019 cm-3 View full abstract»

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  • Tunable, micromachined parallel-plate transmission lines

    Page(s): 201 - 208
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    We have fabricated for the first time cantilevered, tunable, out of the plane transmission lines and demonstrated the active change of impedance levels using banks of finger capacitors as motors. The tunable lines are fabricated in a coplanar waveguide-like configuration thereby making them compatible with existing monolithic millimeter wave devices. The architecture can be readily applied to make variable matching circuits for antennas, and cascading several in series, variable length stubs. The process provides enough flexibility for design variations and future enhancements, for instance, n-switching devices, filters and phase array antennas. This novel device is simple, monolithic, does not require any high temperature steps, and can therefore, be readily incorporated to other processes View full abstract»

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  • High uniformity 75 GHz junction HEMTs (JHEMTs) using a dry-etch gate technology

    Page(s): 532 - 541
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    This paper demonstrates a high uniformity 75 GHz (fτ) GaInAs junction HEMT (JHEMT) technology with ±5 percent variations in the DC and RF parameters using a selective dry-etch gate process. This technology is attractive for the manufacturing of low cost MMICs View full abstract»

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