K. P. Roenker

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A new approach to the hardware implementation of artificial, electronic pulse-mode neural circuits is proposed and demonstrated based on the use of a novel heterostructure device that exhibits an S-type current-voltage characteristic. The new device consists of a multi-period quantum well structure with heavily doped n+ GaAs quantum wells and undoped AlGaAs(More)
Because of their superior scaling characteristics and reduced short channel effects, multi-gate MOSFETs are being considered for replacing conventional planar silicon MOSFETs in digital applications. At the same time, improvements in the high frequency capabilities of conventional MOSFETs have made them increasingly attractive for RF applications. The paper(More)
This paper presents a physics-based model describing the current-induced formation of a parasitic barrier in the conduction band at the base-collector heterojunction in n-p-n SiGe heterojunction bipolar transistors (HBTs). Due to the valence band discontinuity /spl Delta/E/sub v/, hole injection into the collector at the onset of base pushout is impeded,(More)
An analytical model which matches thermionic-emission-diffusion of holes across the emitter-base heterojunction with drift-diffusion transport across a graded base has been developed and used to examine the performance capabilities of InP-based Pnp heterojunction bipolar transistors ~HBTs!. Hole drift-diffusion across the emitter-base space charge region is(More)
The performance of InAlAs/InGaAs heterojunction bipolar phototransistors (HBTs) has been studied in order to develop improved photodetectors for use in long wavelength optical receivers based on heterojunction bipolar transistors (HBTs). This paper presents experimental results for devices operated with a base bias and with frontside optical injection(More)
The effects of Shockley–Read–Hall, Auger, radiative, and intrinsic surface base recombination processes in the emitter-base space-charge region on the current gain of Pnp AlGaAs/GaAs heterojunction bipolar transistors are analyzed. At low forward emitter-base bias, the current gain of a typical Pnp AlGaAs/GaAs heterojunction bipolar transistor is shown to(More)
The effects of displacement of the p-n junction with respect to the SiGe-Si heterojunction at both the emitter and collector junctions have been studied using a commercial numerical device simulator. Parasitic barrier formation at both junctions has been quantified and their degrading effects on HBT performance investigated as a function of junction(More)
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