Dc and microwave models for Al(x)Ga(1x)As/GaAs high electron mobility transistors
Abstract
Models are developed for the dc IV curves and microwave smallsignal parameters of the Al(x)Ga(1x)As/GaAs heterojunction fieldeffect transistor, called the high electron mobility transistor (HEMT). An analytic velocity versus field model is used, along with the exact variation with density of the GaAs twodimensional electron gas Fermi level. A numerical integration is used to obtain the drain voltage for a given gate voltage and sourcedrain current. The resulting IV curves are in excellent agreement with the experimental data from four different groups. This model is also used to calculate the transconductance and gate capacitance, and a model is developed for the source resistance. These are used to calculate the maximum frequency of oscillation for a range of values of gate length, of AlGaAs alloy composition and doping, and of the thickness of the undoped AlGaAs spacer layer. The results are compared with measured data for HEMT's as well as for a similar GaAs FET with 0.35micron gate length.
 Publication:

IEEE Transactions on Electron Devices
 Pub Date:
 December 1984
 DOI:
 10.1109/TED.1984.21801
 Bibcode:
 1984ITED...31.1854W
 Keywords:

 Aluminum Gallium Arsenides;
 Gallium Arsenides;
 Heterojunction Devices;
 High Electron Mobility Transistors;
 Microwave Equipment;
 Additives;
 Direct Current;
 Signal Analysis;
 VoltAmpere Characteristics;
 Electronics and Electrical Engineering