Silicon Nitride Thickness Dependent Electrical Properties of InAlN/GaN Heterostructures

Abstract

We have investigated the effects of silicon nitride layer thickness on the passivation of InAlN/GaN-on-Si high electron mobility transistors (HEMTs). It is found that the charge density in the two dimensional electron gas (2DEG) at the InAlN/GaN interface increases with increasing SiN x passivation layer thickness and saturates at an optimal thickness of ~ 100 nm. A systematic red shift in the photoluminescence (PL) peak position of the GaN channel is observed due to the enhancement in 2DEG carrier density related to SiN x layer thickness. Such passivated InAlN/GaN-on-Si HEMTs show increase in the saturation drain current, maximum extrinsic transconductance and negative threshold voltage shifts. A maximum increase of the drain current from 0.64 to 0.92 A/mm, and the peak extrinsic transconductance from 0.165 to 0.206 S/mm are observed for a SiN x thickness of 100 nm and higherWe have investigated the effects of silicon nitride layer thickness on the passivation of InAlN/GaN-on-Si high electron mobility transistors (HEMTs). It is found that the charge density in the two dimensional electron gas (2DEG) at the InAlN/GaN interface increases with increasing SiN x passivation layer thickness and saturates at an optimal thickness of ~ 100 nm. A systematic red shift in the photoluminescence (PL) peak position of the GaN channel is observed due to the enhancement in 2DEG carrier density related to SiN x layer thickness. Such passivated InAlN/GaN-on-Si HEMTs show increase in the saturation drain current, maximum extrinsic transconductance and negative threshold voltage shifts. A maximum increase of the drain current from 0.64 to 0.92 A/mm, and the peak extrinsic transconductance from 0.165 to 0.206 S/mm are observed for a SiN x thickness of 100 nm and higher

Mobility and Sheet Charge in High-Electron Mobility Transistor Quantum Wells From Photon-Induced Transconductance

“…For example in GaN-based devices, certain passivation coatings are used to increase the density of surface state, which in turn, increase the density of charge in the 2-dimensional electron gas (2DEG). 9,10 These changes may vary among different transistors on the same wafer. Measuring mobility in the transistor has so far been limited to measuring the field-effect mobility that has been shown to be prone to errors especially in devices having extreme electron mobilities.…”