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Presents an exact solution of the magnetic-field-dependent Hall and conductivity equations and their application to modulation-doped field-effect transistors (MODFET). Common components of a MODFET; Hindrance in assessing the Hall effect in a MODFET; Derivation of equation expressing dependences of conductivity and Hall coefficient on magnetic fields of degenerate bands.

Presents an experimental data in support of a transport process in resonant tunneling diodes (RTD) with spacer layers. Procedure; Structure of the devices investigated in the study.

Presents a self-consistent calculation of the electron density and conduction-band edge. States that are capable of trapping a substantial amount of charge; Schemes used for the quantitative prediction of the terminal current-voltage characteristic of quantum well diodes; Capability of a quasi-two-dimensional system of states.

Presents a study that investigated the characteristics of aluminum arsenide/gallium arsenide superlattice barriers using electrical barrier height analysis. Methodology; Determination of the superlattice barrier layer thickness; Comparison of the superlattice barrier of gallium arsenide and aluminum arsenide.

This paper reports a frequency-agile and power scalable power amplifier (PA) utilizing solid-state gallium nitride (GaN) radio frequency (RF) switches to enable selectable input and output matching networks suitable for L- and S-band telemetry (TM) applications. At L-band, the PA yields 9.4 dB compressed gain, 44.8% peak power-added efficiency (PAE), and 29.7 dBm of output power (Pout). This same PA can be switched to operate in S-band yielding 10.8 dB gain, 55% peak PAE, and 29.8 dBm output power. By varying the drain bias, the PA output power is scalable from 250 mW at 10 V drain to 3.5 W at 40 V drain, resulting in 10X power scaling. In addition, the PA is packaged and characterized using a 10 Mbps shaped-offset quadrature phase shift keying (SOQPSK) waveform at L-band and S-band. Measured results show the PA has minimum phase error contribution of 0.01 ° root mean square (RMS) and a 0.09 ° peak phase error. This is the first reported frequency-agile GaN microwave monolithic integrated circuit (MMIC) PA design specifically for telemetry applications. [ABSTRACT FROM AUTHOR]

Quantum well diodes with barriers formed by thin, short-period binary AlAs/GaAs superlattices were fabricated and found to have very high peak-to-valley current ratios. The effects of varying the AlAs and GaAs layers in the barriers are studied. The peak current density is found to decrease by orders of magnitude for monolayer increases in the AlAs layer thicknesses. Tunneling current peaks due to both resonance levels in the quantum well and resonance levels in the superlattice barriers are observed. [ABSTRACT FROM AUTHOR]

We report the largest peak-to-valley current (PVC) ratios to date from AlGaAs/GaAs double barrier (either alloy barrier or superlattice barrier) diodes. PVC ratios as high as 3.6 and 21.7 were obtained from an AlAs/GaAs superlattice barrier structure at 300 and 77 K, respectively. In an alloy barrier structure with x=0.42 (x=0.3), PVC ratios of 3.9 (2.2) and 14.3 (7.0) were observed at 300 and 77 K, respectively. We attribute these excellent results to a ‘‘two-step’’ spacer layer incorporated in the devices studied which facilitated the growth of high material quality. [ABSTRACT FROM AUTHOR]