Yasuko Hori

Analysis of electric field distribution in GaAs metal–semiconductor field effect transistor with a field-modulating plate

Electric field distribution in the channel of a field effect transistor (FET) with a field-modulating plate (FP) has been theoretically investigated using a two-dimensional ensemble Monte Carlo simulation. This analysis revealed that the introduction of FP is effective in canceling the influence of surface traps under forward bias conditions and in reducing the electric field intensity at the drain side of the gate edge under pinch-off bias conditions. This study also found that a partial overlap of the high-field region under the gate and that at the FP electrode is important for reducing the electric field intensity. The optimized metal–semiconductor FET with FP (FPFET) (LGF∼0.2 μm) exhibited a much lower peak electric field intensity than a conventional metal–semiconductor FET. Based on these numerically calculated results, we have proposed a design procedure to optimize the power FPFET structure with extremely high breakdown voltages while maintaining reasonable gain performance.

Improved model for kink effect in AlGaAs/InGaAs heterojunction FET's

The kink effect in an AlGaAs/InGaAs HJFET has been investigated with regard to optical wavelength, temperature and gate voltage. The study reveals that the drain current value measured at the drain voltage lower than the kink voltage increases by irradiating white light onto the device, indicating the irradiation-induced kink effect recovery. The degree of the kink disappearance exhibited a significant optical wavelength dependence. We also found that the kink effect is suppressed either by increasing the temperature or by applying a high gate voltage where parallel conduction takes place. Based on these experimental results, we propose an improved model for the kink effect in an AlGaAs/InGaAs HJFET in which the kink effect is closely related to carrier trapping at the hole traps in the AlGaAs donor layer. >

Effect of strain on band structure and electron transport in InAs

Abstract We have theoretically investigated the band structure of InGaAs and strained InAs on (001) InP by employing the pseudopotentials and the local density approximation. We have extracted band parameters and analyzed electron transport by the Monte Carlo method. 26% higher mobility and 16% higher peak velocity are predicted in strained InAs in comparison with unstrained In 0.53 Ga 0.47 As.

Bias-dependent collapse and its recovery phenomenon in AlGaAs/GaAs 2DEGFETs at low temperatures

Current-voltage characteristics for AlGaAs/GaAs 2DEGFETs (two-dimensional electron gas FETs) have been investigated at low temperatures in terms of stress biases and stress time. The study reveals that the degree of collapse strongly depends on the magnitude of the stress drain voltage. The device exhibits seriously collapsed I-V characteristics when the stress drain voltage is chosen at around 1.2 V. Application of higher stress drain voltages leads to less distorted I-V characteristics, demonstrating a collapse-recovery mechanism without the need for illuminating or heating the device, and therefore the heavily collapsed state and the recovered state can be switched with each other by simply changing the value of the stress drain voltage. Based on the gate current analysis during the bias stress step, the authors attribute the mechanism responsible for the drain-stress-induced recovery phenomenon to the ionization of DX centers by capture of holes generated by impact ionization. >

Intermodulation distortion simulation using physical GaAs FET model

Intermodulation distortion is simulated using a physical GaAs FET model for the first time, to our knowledge. A GaAs FET power amplifier, including input and output circuits, is examined. For the FET, a fully 2-dimensional Monte Carlo simulator is used. The simulated P/sub IN/-P/sub OUT/ performance is in fair agreement with measured data. Gain and phase compression (AM-PM) characteristics are simulated, and correlated to features in the RF I-V characteristics. Finally, third order intermodulation distortion is estimated from the AM-PM characteristics and compared to measurement, with qualitative agreement. This technique advances the art of computer aided design of nonlinear devices because it allows the prediction of distortion characteristics before undertaking an expensive and time-consuming device fabrication.

Monte Carlo simulation for electron transport in MESFETs including realistic band structure of GaAs

A full band Monte Carlo (FBMC) simulator was developed for electron transport in GaAs MESFETs. As a result of increased scattering rate due to the complicated band structure, the average velocity in the high field region was lower than the analytical band Monte Carlo (ABMC) result. Also, the simulated energy peak was higher than the ABMC result, due to electrons populating the upper bands. Not only due to a limited number of the first conduction band states capable of ionization, but also due to a small mass of the second conduction band, more than 95% of ionization events were shown to occur in the upper bands. The simulated ionization rate lies within the range of experimental results. To our knowledge, this is the first report on the full band two-dimensional (2-D) self-consistent GaAs MESFET simulation.

First principles band structure calculation and electron transport for strained InAs

We have theoretically investigated the band structure of InGaAs and strained InAs on [001] InP by employing the pseudopotentials and the local density approximation. We have extracted band parameters and analyzed electron transport by the Monte Carlo method. 26% higher mobility and 16% higher peak velocity are predicted in strained InAs in comparison with unstrained In/sub 0.53/Ga/sub 0.47/As.

Full band Monte Carlo simulation for temperature-dependent electron transport in gallium nitride

Abstract A fast and compact full band Monte Carlo electron transport simulator has been developed, which can run on a personal computer. High-temperature transport simulation was demonstrated for GaN, and it predicts small temperature dependence of peak velocity and reduction of impact ionization at high temperature.

InP-based heterojunction FET processing for high-reliability millimeter-wave applications

Describes a novel InP-based FET processing technology for high-reliability microwave applications. High performance InAlAs/InGaAs heterojunction FETs (HJFETs) were fabricated using completely molybdenum-based electrode technology (COMET). The fabricated 1 /spl mu/m gate-length COMET-HJFET exhibited excellent DC and RF performance, including a transconductance of 470 mS/mm and a current gain cutoff frequency of 40 GHz. High temperature DC bias tests performed on the COMET device demonstrated improved reliability compared to that for the conventional InP-based HJFET. The superior reliability of the developed COMET-HJFET is attributed to the reduced interdiffusion between metals of the electrodes and semiconductors by introducing a refractory metal of Mo as a barrier metal.