Effect of in-situ SiNx grown with different carrier gas on structural and electrical properties of GaN-based MISHEMTs

In this work, the effect of in situ SiNx grown with different carrier gas on the structural and electrical properties of the SiNx/AlGaN/GaN MIS-HEMTs is studied. It was found that the growth rate of SiNx grown with N-2 as carrier gas (N-2-SiNx) is more sensitive to different growth conditions, while the growth rate of SiNx grown with H-2 as carrier gas (H-2-SiNx) is very stable due to the inhibiting effects of H-2 carrier gas on the SiH4-NH3 forward reactions. More importantly, a continuous and smooth SiNx growth at the initial stage can be realized with H-2 carrier gas due to its faster surface migration, leading to a decent surface morphology and sharp interface of H-2-SiNx. As a result, the SiNx passivated device with H-2 as carrier gas shows improved performance compared to that with N-2 as carrier gas, featuring ultra-low interface-state density of 2.8 x 10(10) cm(-2 )eV(-1), improved on- and off-state current, reduced threshold voltage shift, and mitigated current collapse, especially after long-term electrical stress. These results not only elaborate on the growth mechanisms of in situ SiNx with different carrier gases but also highlight the advances of H-2 as carrier gas for in situ SiNx growth, providing an effective strategy to tailor the passivation schemes for GaN-based devices.