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Electrical and Computer Engineering
Department of Electrical and Computer Engineering Faculty Publications
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Effective Bandgap Shrinkage In Gaas, E. S. Harmon, Michael R. Melloch, Mark S. Lundstrom
Effective Bandgap Shrinkage In Gaas, E. S. Harmon, Michael R. Melloch, Mark S. Lundstrom
Department of Electrical and Computer Engineering Faculty Publications
Electrical measurements of the equilibrium np product (n2ie) in heavily doped n‐ and p‐GaAs were performed. The n2ieDproduct (where D is the diffusivity) was measured by fitting the collector current‐voltage characteristic of a homojunction bipolar transistor to an ideal diode equation modified to account for transport in thin base transistors.The n2ie product was then extracted from n2ieD by utilizing diffusivity results obtained with the zero‐field time‐of‐flight technique. Our results show significant effective band‐gap shrinkage in heavily doped p‐GaAs, and very little effective band‐gap shrinkage …
Thermal Velocity Limits To Diffusive Electron Transport In Thin‐Base Np+N Gaas Bipolar Transistors, E. S. Harmon, Michael R. Melloch, Mark S. Lundstrom, F. Cardone
Thermal Velocity Limits To Diffusive Electron Transport In Thin‐Base Np+N Gaas Bipolar Transistors, E. S. Harmon, Michael R. Melloch, Mark S. Lundstrom, F. Cardone
Department of Electrical and Computer Engineering Faculty Publications
We present experimental evidence that minority electron transport across a thin, quasineutral p+ GaAs region is limited by the thermal velocity of the electrons rather than by conventional diffusive transport. A set of GaAs homojunction np+n transistors with base widths of 4000, 2000, 1000, and 500 Å was fabricated and characterized. The diffusive modelpredicts that the dc collector current of the 500‐Å base width transistors should be eight times larger than the collector current of transistors with a 4000‐Å‐wide base. The experimental results, however, show only a factor of ~3.5 increase in collector current. The measured collector …