Abstract
In this thesis, we compare the DC and RF characteristics of AlGaN/GaN and AlInN/GaN HEMTs and their equivalent small signal signal circuit model are constructed and compared. For the DC characteristics the saturated current density(Idss) and the transconductance(Gm) of the AlInN/GaN HEMT is 1271mA/mm and 231mS/mm respectively which are higher than the AlGaN/GaN’s value 900mA/mm and 187mS/mm because of the higher 2DEG concentration in AlInN/GaN. But the leakage current of the AlInN/GaN HEMT is also higher than that of AlGaN/GaN HEMT. For high frequency characteristics, the AlInN/GaN HEMT shows an ft=82GHz and an fmax=70GHz, which is also higher than the AlGaN/GaN’s numbers because of the higher transconductance of AlInN/GaN HEMT. But for RF power characteristics the AlInN/GaN HEMT is poor than AlGaN/GaN HEMT due to the higher leakage current of AlInN/GaN HEMT. Finally we extract small signal parameters, contstruct equivalent circuit models, and compare their intrinsic values. From the extracted values, It is found that the intrinsic gm of AlInN/GaN HEMT is higher than the AlGaN/GaN which is also attributed to the higher carrier density on the AlInN/GaN wafer.