Fabrication and characterization of GaN HEMTs grown on SiC substrates with different orientations

摘要

This article reports the fabrication and characterization of metal-semiconductor high electron mobility transistors (MS-HEMT) and metal-oxidesemiconductor (MIS-HEMT) grown on the semi-insulating SiC substrates with 0 degrees and 4 degrees-off axis. For the MIS-HEMT, the HfO2 film was used as the insulator deposited by atomic layer deposition. With a gate length of 2 mu m, MS-HEMT and MIS-HEMT devices with 4 degrees-off SiC substrates exhibit a drain saturation current density (J(DS,max)) of 895 and 1016 mA/mm, the maximum transconductance (G(m,max)) of 225 and 175 mS/mm, a cut-off frequency (f(T)) of 8.1 and 9.4 GHz, and a maximum oscillation frequency (f(max)) of 22 and 27.4 GHz, respectively, which are better than those with 0 degrees SiC substrates. Furthermore, the devices with 4 degrees-off substrate are verified with less interface states and buffer traps through the temperature-dependent and pulse current-voltage measurements.