Lateral resonant tunneling transistors employing field-induced quantum wells and barriers

Article Abstract:

The scaled transistors of the future may be smaller than 100 nm and capable of operating at low enough temperatures for quantum effects to be significant. These effects are undesirable for conventional transistors, but future devices may be able to utilize them effectively. Preliminary experiments with the quantum-effect modulation-doped field-effect transistors (MODFET's) are described with a variety of nanometer gate geometries. These gate geometries were conducive to the formation of various quantum wells and barriers in the channel of the MODFET's through-the-field-effect imposed by novel gate structures. The electrons' transport was affected by resonant tunneling. A combination of molecular beam epitaxy and electron beam lithography was used to fabricate the devices. The devices showed resonant tunneling effects at 4.2 K; resonant tunneling is more pronounced for a system of quantum wells confined in three dimensions than in two. The feature size of the gate geometries should be under 50 nm for these quantum effects to be appreciable at practical temperatures.

Semiconductors and related devices, Quantum electronics, Technical, Temperature, Gates, Transistor

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Pulse response characteristics of GaAs MESFET distributed amplifiers

Article Abstract:

The pulse response characteristics of broad-band gallium arsenide (GaAs) MESFET distributed amplifiers are examined using five Honeywell 300-micrometer GaAs FET stages. The amplifiers are measured and their data analyzed to show close agreement with measured sinusoidal gain at small-signal levels. Expected gain compression is shown to occur for large-signal input. Pulse distortion is shown to be negligible even for pulse heights comparable to FET pinchoff.

Audio amplifiers, Gallium arsenide semiconductor devices, Gallium Arsenide Semiconductors, Pulse Amplitude Modulation, Amplifiers, Audio

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Parallel Operation of Power Transistors in Switching Amplifiers

Article Abstract:

Low power dissipation is the result of adding base resistors to parallel transistors in switching-mode power amplifiers to equalize collector currents. Experimental results confirm the operation of the circuit. Circuit diagrams are given along with equalized collector current waveforms.

Switches, Power semiconductor devices, Power Dissipation, Amplifiers

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