RF PERFORMANCE ASSESSMENT OF AlGaN/GaN MISHFET AT HIGH TEMPERATURES FOR IMPROVED POWER AND PINCH-OFF CHARACTERISTICS

An investigation of temperature model for an AlGaN/GaN MISHFET is presented and a relative comparison is done with conventional HFET structures. The proposed analytical model demonstrates its inherent ability to operate at higher temperature. The contributions from various temperature dependent material parameters are taken into account along with the effect of temperature on the sheet carrier concentration and threshold voltage of the device. The model is further extended to predict the temperature dependence of transconductance, cat off frequency and pinch-off characteristics. The investigated temperature range is from 25 degrees C-300 degrees C Non linear Fermi potential (E-f) variation with the sheet carrier concentration (n(s)), and the highly dominant effects of spontaneous and piezoelectric polarization at the AlGaN/GaN heterointerface are also considered. AlGaN/GaN MISHFETs demonstrate larger drain currents, cut-off frequency, and better pinch-off characteristics at high temperatures. The model is based on closed from expression and does not involve elaborate computation. The analytical results on the transport characteristics of both the devices are compared with available experimental data and are in good agreement. (C) 2009 Wiley Periodicals. Inc. Microwave Opt Technol Lett 51: 1942-1949, 2009: Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24461