A Method for Obtaining the Real Off-State Breakdown Voltage of AlGaN/GaN MIS-HEMTs in On-Wafer Tests by Optimizing Protective Layer

We demonstrate a method for testing the real off-state breakdown voltage (
$\text{V}_{\mathrm{ BD}}$
) of AlGaN/GaN metal–insulator-semiconductor high electron mobility transistor (MIS-HEMTs) in on-wafer tests. The method prevents the arcing over air at high voltage by depositing the protective layer between the pad electrodes of source and drain. The influence of materials and thickness of the protective layer on the high voltage tests of MIS-HEMTs were investigated. We found that it is helpful to obtain the real
$\text{V}_{\mathrm{ BD}}$
of the devices by increasing the thickness of the protective layer and selecting a material with a higher critical breakdown field strength. The real
$\text{V}_{\mathrm{ BD}}$
of the device with a gate-to-drain spacing of 25
$\mu \text{m}$
is 1164 V when 1.5
$\mu \text{m}$
SiO
₂
is deposited as the protective layer, which is 141% higher than that of the value tested in air.