Silicon Nitride Stress Liner Impacts on the Electrical Characteristics of AlGaN/GaN HEMTs

Abstract

Due to the piezoelectric nature of GaN, the two-dimensional electron gas (2DEG) in AlGaN/GaN high electron mobility transistor (HEMT) could be engineered by strain. In this work, SiN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> deposited using dual-frequency plasma-enhanced chemical vapor deposition (PECVD) was used as a stressor. The output performance of the devices was dominated by the surface passivation instead of the strain effect. However, the threshold voltage was increased by the liner-induced strain, supporting strain engineering as an effective approach to pursue the normally-off operation of AlGaN/GaN HEMTs.