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Electron Device Letters, IEEE

Issue 5 • Date May 1982

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Displaying Results 1 - 16 of 16
  • [Front cover and table of contents]

    Page(s): c1
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    Freely Available from IEEE
  • A new Al0.3Ga0.7As/GaAs modulation-doped FET

    Page(s): 109 - 111
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    A new Al0.3Ga0.7As/GaAs modulation-doped FET fabricated like a MESFET but operating like a JFET was successfully fabricated and tested. This new device replaces the Schottky gate of the MESFET with an n+/p+ camel diode structure, thereby allowing problems associated with the former to be overcome. The devices, which were fabricated from structures grown by molecular beam epitaxy (MBE), had a 1µm gate length, a 290µm gate width, and a 4µm channel length. The room temperature transconductance normalized to the gate width was about 95 mS/mm, which is comparable to that obtained in similar modulation-doped Schottky barrier FET's. Unlike modulation-doped Schottky barrier FET's, fabrication of this new device does not require any critical etching steps or formation of a rectifying metal contact to the rapidly oxidizing Al0.3Ga0.7As. Relatively simple fabrication procedures combined with good device performance make this camel gate FET suitable for LSI applications. View full abstract»

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  • Obtaining the specific contact resistance from transmission line model measurements

    Page(s): 111 - 113
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    In characterizing ohmic contacts using the transmission line model, it is necessary to make a measurement referred to as the contact end resistance, as a result of modification to the sheet resistance under the contact. In this article we show that this contact end resistance and the consequent specific contact resistance can be deduced from simple resistance measurements carried out between contacts on a standard, transmission line model test pattern. View full abstract»

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  • High efficiency a-Si:H p-i-n solar cell using a SnO2/glass substrate

    Page(s): 114 - 115
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    Dependence of conversion efficiency of a-Si:H p-i-n solar cells on the material of transparent conductive film substrates was studied. Irrespective of preparation method of the transparent conductive film, SnO2films gave an advantage over ITO films for high efficiency cell production by a parallel plate electrode type plasma C.V.D. equipment. A conversion efficiency of 7.19% was achieved by optimizing preparation conditions of the SnO2film and the a-Si:H film. View full abstract»

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  • Laser activated flow of phosphosilicate glass in integrated circuit devices

    Page(s): 116 - 118
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    The use of a cw CO2laser to flow phosphosilicate glass for the planarization of p+/n diode arrays is demonstrated. A power density flow threshold of 110 kW cm-2at a wavelength of 9.26 µm is estimated and found to be essentially invariant to the thickness of the glass (1.0 to 1.5 µm) and to the phosphorus concentration of the glass (3 to 9% wt). This laser activated process results in glass flow without impurity diffusion in the active device area and is therefore compatible with VLSI. View full abstract»

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  • A new ZnO-on-Si convolver structure

    Page(s): 118 - 120
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    A new surface acoustic wave (SAW) convolver has been fabricated on a silicon substrate. The device employs a planar-processed, high-speed DMOS transistor as a mixer to implement the convolution cross terms, utilizing the nonlinear dependence of drain current on gate voltage. The input waveforms are SAW's at 45 MHz, and the interaction path length is 0.9 mm. A value of -29 dbm is obtained for the internal bilinear conversion efficiency Fint. View full abstract»

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  • Determination of built-in-potential in N-I-P a-Si:H solar cells

    Page(s): 121 - 124
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    This paper describes a simple method to evaluate built-in-potential of P-N junction a-Si:H solar cells. Built-in-potential (Vbi) was calculated from photovoltage-current characteristics at various temperature and illumination levels. Results from two independent, experimental techniques agree extremely well. Vbi= 1.02 eV ± 0.02 eV was obtained for a N-I-P cell having Voc= 650 mV under AM1 illumination. View full abstract»

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  • Performance prediction for submicron GaAs SDFL logic

    Page(s): 124 - 127
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    We report the results of the computer simulation of GaAs SDFL (Schottky diode FET logic) ring oscillators which takes into account transient effects leading to higher electron velocity in short devices and the fringing capacitances. The results indicate that the delay time decreases from 53.6 ps for 1 µm devices to 28.1 ps for 0.5 µm gate devices, and to 18.6 ps for 0.25 µm devices, with power-delay products of 229, 70, and 27.1 fJ, respectively. When the transient effects are not taken into account, the power-delay product remains nearly the same but the delay time increases with the largest increase to 27 ps for .25 µm devices. View full abstract»

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  • Tantalum oxide capacitors for GaAs monolithic integrated circuits

    Page(s): 127 - 129
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    The performance of a high-yield tantalum oxide capacitor for use in GaAs monolithic microwave integrated circuits is described. The integral metal-insulator-metal sandwich structure is reactively sputter-deposited at low temperatures, compatible with a photoresist lift-off process, on semi-insulating GaAs substrate. Dielectric constants of 20-25 were achieved in the capacitors fabricated. An initial application of this process as an interstage coupling capacitor for a two-stage preamplifier is given. View full abstract»

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  • High speed response InGaAsP/InP DH LED's in the 1 µm wavelength region

    Page(s): 129 - 131
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    The frequency response of a fiber-coupled LED with a small diameter contact has been studied. It has been shown that the current spreading occurring at the contact edge causes an appreciable response speed reduction. However, this was found to be eliminated by a monolithic lens formed on the LED surface, which can make only the light generated at the center of the contact coupled into a fiber. This technique was successfully applied to fabricate high speed InGaAsP/ InP DH LED's at wavelengths of 1.15 µm, 1.3 µm, and 1.5 µm. The 1.3 µm LED's exhibited the -1.5 dB cutoff frequency of 80 MHz, typically at 100 mA current without reduction of the coupled power. View full abstract»

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  • Errata

    Page(s): 131
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  • An open tube method of Zn diffusion in III-V compounds

    Page(s): 132 - 134
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    A novel method for diffusing volatile impurities (such as Zn) in III-V compounds has been developed. The apparatus described here maintains an appropriate vapor pressure of Zn in a localized and confined manner in close proximity over the III-V compound wafer. This technique is used for diffusing Zn in InP. View full abstract»

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  • Demonstration of electrical performance of QGBF polysilicon solar cell structure

    Page(s): 134 - 137
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    Small-area p/n junction photodiodes have been fabricated on Wacker polysilicon material using the novel concept of quasi-grain-boundary-free (QGBF) solar cells. The use of small-area structures simulates the predominance of grain-boundary recombination in determining the conversion efficiency in small-grain polysilicon solar cells. The electrical performance of the QGBF test photodiodes is shown to be comparable to single crystal photodiodes fabricated on the same wafer. View full abstract»

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  • In-situ low energy BF2+ion doping for silicon molecular beam epitaxy

    Page(s): 138 - 140
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    An experimental study of the p-type ion dopant BF2+ in silicon molecular beam epitaxy (MBE) is described. BF2+ was used to dope MBE layers during growth to levels ranging from 1 × 1016/cm3to 4 × 1018/cm3over a growth temperature range of 650°C to 1000°C. The layers were evaluated using spreading resistance, chemical etching, and secondary ion mass spectroscopy. Complete dopant activation was observed for all growth temperatures. Remnant fluorine in the epitaxial layer was less than 2 × 1016/cm3in all cases. Diffused p-n junction diodes fabricated in BF2+-doped epitaxial material showed hard reverse breakdown characteristics. View full abstract»

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  • Conduction in polycrystalline silicon: Diffusion theory and extended state mobility model

    Page(s): 141 - 143
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    We present a new model for conduction in polycrystalline silicon based on an extended state mobility in the disordered grain boundary and the diffusion theory of current. This analysis for the first time satisfactorily explains-without the use of scaling or artificial factors-experimental data on current density, mobility, resistivity, and the activation energy for carriers in polysilicon. An attractive feature of this theory is that it provides simple expressions for J, µ, and ρ which may even be derived from an equivalent circuit model. Also, these expressions reduce, within appropriate limits, to the corresponding terms for single crystal or amorphous material. View full abstract»

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  • [Back cover]

    Page(s): c4
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    Freely Available from IEEE

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