Temperature‐dependent microwave noise performances of AlGaN/GaN HEMTs with post‐gate annealing

Abstract

In this paper, we report the temperature dependence of microwave noise performances of AlGaN/GaN high electron mobility transistors (HEMTs) up to 573 K and the influences of post-gate-annealing (PGA) technique on temperature dependant characteristics of HEMTs. From room temperature (R.T.) to 573 K, the maximum current of devices with PGA decreased from 998 mA/mm at R.T. to 478 mA/mm while maximum current of devices without PGA dropped from 848 mA/mm at R.T to 641 mA/mm at 393 K. The gate leakage current of devices with PGA is four orders smaller than that of devices without PGA. For RF performance, the cut-off frequency (fT) and the maximum frequency of oscillation (fmax) of devices decreased significantly with increasing temperature. In noise measurements, annealed devices exhibited significant improvements in minimum noise figure (NFmin) and associated gains (Ga). Specifically, NFmin and Ga at 10 GHz are measured at different temperatures. At R.T., the devices after PGA showed an NFmin of 1.16 dB that was 0.7 dB lower than the un-annealed devices. At 573 K, the devices with PGA still exhibit excellent characteristics with an NFmin of 3.94 dB and a Ga of 7.02 dB while devices without PGA can only work up to 393 K. To our knowledge, this is the first report of microwave noise performances of AlGaN/GaN HEMTs for substrate temperatures higher than 473 K. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)