Effect of <italic>In-Situ</italic> Silicon Carbon Nitride (SiCN) Cap Layer on Performances of AlGaN/GaN MISHFETs

Abstract

AlGaN/GaN metal insulator semiconductor heterostructure field effect transistors (MISHFETs) with different thickness of in-situ silicon carbon nitride (SiCN) cap layer were investigated. It was found that in-situ SiCN layer not only increases the two dimensional electron gas (2DEG) density, but also effectively passivates the surface of the AlGaN/GaN MISHFET. The fabricated device with 2 nm-thick SiCN cap layer exhibits superior device performances, such as larger maximum transconductance ( $\text{g}_{\mathrm{ m}}$ ) and higher on/off drain-current ratio ( $\text{I}_{\mathrm{ ON}}/{\mathrm{ I}}_{\mathrm{ OFF}}$ ) compared to those of the device without SiCN cap layer.

Keywords

• AlGaN/GaN
• metal insulator semiconductor heterostructure field effect transistors (MISHFETs)
• in-situ silicon carbon nitride (SiCN)
• cap layer
• 2DEG density
• surface leakage current