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M.S. Defense Wednesday, May 9, 2007 ENG II – Room 202 11:00AM Title: Ambient Temperature Effects on the Performance of AlGaN/GaN Field-Effect Transistors Abstract: GaN-based heterostructure field-effect transistors are attracting significant attention as promising candidates for the high-frequency and high-power applications. AlGaN/GaN field-effect transistors have demonstrated the ability to operate at frequencies above 10 GHz while providing power levels exceeding 11 W/mm. These devices are capable of working with low flicker noise levels comparable to those in conventional Si and GaAs transistors. For applications in remotely controlled vehicles, the stability of device operation under changing temperature is of critical importance. An increase in ambient temperature coupled with strong self-heating effects in high-power GaN transistors may result in performance degradation. The thermal structure resistance also increases at high temperature due to the decrease of the thermal conductivity. This thesis describes research focused on the experimental and computer simulation study of the effect of ambient temperature on the performance of the AlGaN/GaN heterostructure field-effect transistors. The temperature effect was studied experimentally in the temperature range from 300K to 500K. The measured data have been used for validation of the physics-based modeling of the GaN transistor characteristics under different ambient temperatures. The experimental data, showing degradation in the saturation current with increasing temperature, agrees well with the the computer simulations. Obtained results can be used for predicting device performance in changing environments, as well as for the optimization of the device structure. |
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