High temperature performance and low frequency noise characteristics of AlGaN/GaN/AlGaN double heterostructure metal-oxide-semiconductor heterostructure field-effect-transistors with photochemical vapor deposition SiO₂ layer

High quality SiO₂ films were successfully deposited onto AlGaN using photochemical vapor deposition (photo-CVD). The interface state density, D_it, of photo-CVD SiO₂ was estimated to be only 1.1 × 10¹¹ cm^-2eV^-1 at room temperature and still only 3.5 × 10¹²cm^-2eV^-1 even at 175°C. With a 1 μm gate length, it was found that the maximum saturated drain-source current (I_ds), maximum transconductance (g_m) and gate voltage swing (GVS) of the AlGaN/GaN/AlGaN double heterostructure metal-oxide-semiconductor heterostructure field-effect-transistors (MOS-HFETs) fabricated were 755mA/mm, 95 mS/mm and 8 V, respectively. Even at 300°C, the maximum saturated I_ds and maximum g_m of the MOS-HFETs fabricated were still kept at 527 mA/mm and 77 mS/mm, respectively. Furthermore, from the low frequency noise power spectrum, it was found that noise power density of the AlGaN/GaN/AlGaN double heterostructure was lower and presented pure 1/f noise with smaller trapping effects than conventional structures.