Impact of Surface Passivation on the Dynamic ON-Resistance of Proton-Irradiated AlGaN/GaN HEMTs

Abstract

Radiation tolerance of AlGaN/GaN high-electron mobility transistors (HEMTs) is studied with 2-MeV protons, up to a fluence of 6×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">14</sup> H <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> /cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> (about 200 times of typical Si MOSFET rating). The increase in dynamic ON-resistance (R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ONDYN</sub> ) after radiation is observed to be much more severe than that of static ON-resistance. Radiation-induced donorlike traps located near the two-dimensional electron gas trap electrons, which is responsible for the phenomenon. Compared with the devices passivated by conventional plasma-enhanced chemical vapor deposition (PECVD) SiN, GaN HEMTs with 10 nm of in situ SiN before the PECVD SiN step demonstrate much less increase in R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ONDYN</sub> from 2300% to only 300%. The in situ SiN is believed to reduce the process damage by PECVD, improving radiation tolerance.