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 NiO
_X
/SiN
_X
and Al
₂
O
₃
/SiN
_X
respectively, act as gate dielectric layer and passivation layer for the devices. The NiO
_X
and Al
₂
O
₃
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 SiN
_X
is deposited by plasma-enhanced chemical vapor deposition. Compared to the single SiN
_X
layer, the NiO
_X
/SiN
_X
stack layer and Al
₂
O
₃
/SiN
_X
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 NiO
_X
/SiN
_X
stack layer and Al
₂
O
₃
/SiN
_X
stack layer are 52% and 36% higher than that of the devices with single SiN
_X
layer respectively. Especially, the current collapse under 200 V stress bias is reduced by 90% and 58% in the devices with NiO
_X
/SiN
_X
stack layer and Al
₂
O
₃
/SiN
_X
stack layer compare to the devices with single SiN
_X
layer respectively.