Title :
A self-backgating GaAs MESFET model for low-frequency anomalies
Author :
Lee, Mankoo ; Forbes, Leonard
Author_Institution :
Dept. of Electr. & Comput. Eng., Oregon State Univ., Corvallis, OR, USA
fDate :
10/1/1990 12:00:00 AM
Abstract :
A self-backgating GaAs MESFET model which can simulate low-frequency anomalies has been developed by including deep-level trap effects. These cause transconductance reduction due to electron emission from EL2 in the depletion width change at the edge of the Schottky gate junction and the output conductance to increase due to the time-dependent net negative charge concentration in the semi-insulating substrate as a result of self-backgating with the applied signal frequency. This model has been incorporated in PSPICE and includes a time-dependent I-V curve model, a capacitance model, an RC network describing the effective substrate-induced capacitance and resistance, and a switching resistance providing device symmetry. An analytical capacitance model describes the dependence of capacitance on Vgs and Vds and includes the channel-substrate junction modulation by the self-backgating effect. A transit-time delay is also included in the transconductances, gm and gmbs, for model accuracy and to describe the phase shift of S-parameters. Measured data correspond to simulations by this model of the low-frequency anomalous characteristics, voltage-dependent capacitances, and S-parameters of conventional GaAs MESFETs for linear and microwave circuit design
Keywords :
III-V semiconductors; Schottky gate field effect transistors; gallium arsenide; semiconductor device models; solid-state microwave devices; EL2; GaAs; PSPICE; RC network; S-parameters; Schottky gate junction; analytical capacitance model; capacitance model; channel-substrate junction modulation; deep level traps; deep-level trap effects; dependence of capacitance; depletion width change; device symmetry; effective substrate-induced capacitance; electron emission; low-frequency anomalies; output conductance; phase shift of S-parameters; self backgating MESFET model; self-backgating effect; semi-insulating substrate; semiconductors; substrate induced resistance; switching resistance; time-dependent I-V curve model; time-dependent net negative charge concentration; transconductance reduction; transit-time delay; voltage-dependent capacitances; Analytical models; Capacitance; Electron emission; Electron traps; Frequency; Gallium arsenide; MESFETs; SPICE; Scattering parameters; Transconductance;
Journal_Title :
Electron Devices, IEEE Transactions on