High Channel Conductivity, Breakdown Field Strength, and Low Current Collapse in AlGaN/GaN/Si <inline-formula> <tex-math notation="LaTeX">$\delta$ </tex-math> </inline-formula>-Doped AlGaN/GaN:C HEMTs

Abstract

This paper reports the AlGaN/GaN/ Si δ-doped AlGaN/GaN:C HEMT device on silicon with high channel conductivity, high breakdown field (E-field) strength, and low current collapse by using the Si-doped AlGaN back barriers. The Si δ-doped AlGaN back barrier was used to compensate for the reduction of channel conductivity as a result of a carbon-doped semiinsulating GaN buffer layer. The maximum drain current increases from 412 to 720 mA/mm, and peak extrinsic transconductance is improved from 103 to 210 mS/mm. Due to the reduction of electric field between the gate and drain along the GaN channel by inserting the Si δ-doped AlGaN back barrier layer, it can effectively suppress the capture of electrons in channel by carbon-induced accepted traps in the GaN:C buffer. Combined with the high conductivity of Si δ-doped AlGaN back barrier and high resistance of GaN:C buffer, the device showed the high breakdown E-field strength and the low specific on-resistance. Our proposed device is observed to hold a gate-drain voltage of 769 Vat 10 μA/mm (7-μm gate-drain spacing) and 0.53 mQ · cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and the gateto-drain electric field corresponds to 1.1 MV/cm.