Epitaxial buffer structures grown on 200 mm engineering substrates for 1200 V E-mode HEMT application

Abstract

In this work, we demonstrate the epitaxial growth of a gallium-nitride (GaN) buffer structure qualified for 1200 V applications on 200 mm engineered poly-AlN substrates with hard breakdown >1200 V. The manufacturability of a 1200 V qualified buffer structure opens doors to high voltage GaN-based power applications such as in electric cars. Key to achieving the high breakdown voltage is careful engineering of the complex epitaxial material stack in combination with the use of 200 mm engineered poly-AlN substrates. The CMOS-fab friendly engineered poly-AlN substrates have a coefficient of thermal expansion (CTE) that closely matches the CTE of the GaN/AlGaN epitaxial layers, paving the way for a thicker buffer structure on large diameter substrates, while maintaining the mechanical strength of the substrates and reaching higher voltage operation.