Breakdown Enhancement and Current Collapse Suppression in AlGaN/GaN HEMT by NiOX/SiNX and Al2O3/SiNX as Gate Dielectric Layer and Passivation Layer

We propose two kinds of stacked materials that effectively yield low drain off-state leakage current, high off-state breakdown voltage and low current collapse simultaneously in AlGaN/GaN HEMT. The two kinds of stacked materials, which is NiOX/SiNX and Al2O3/SiNX respectively, act as gate dielectric layer and passivation layer for the devices. The NiOX and Al2O3 are prepared through depositing Ni and Al thin film by electron beam evaporation and then annealing in O-2 ambient by rapid thermal processing. The SiNX is deposited by plasma-enhanced chemical vapor deposition. Compared to the single SiNX layer, the NiOX/SiNX stack layer and Al2O3/SiNX stack layer can distinctly reduce the drain off-state leakage current of devices. Meanwhile, high off-state breakdown voltage is also achieved. The off-state breakdown voltage in the devices with NiOX/SiNX stack layer and Al2O3/SiNX stack layer are 52% and 36% higher than that of the devices with single SiNX layer respectively. Especially, the current collapse under 200 V stress bias is reduced by 90% and 58% in the devices with NiOX/SiNX stack layer and Al2O3/SiNX stack layer compare to the devices with single SiNX layer respectively.