(Invited) Selective Area Growth, Etching, and Doping of GaN By MOCVD for Power Electronics

Abstract

Gallium Nitride (GaN) possesses a wide band gap and excellent transport properties, making it a highly promising material for high-power and high-frequency applications. Microwave power amplification for commercial and military purposes has already benefited from GaN-based high electron mobility transistors (HEMTs). However, currently available GaN optoelectronic and electronic devices use planar junctions and heterostructures prepared by epitaxy, typically via metalorganic chemical vapor deposition (MOCVD). To enable more sophisticated device configurations, in-plane lateral junctions are necessary. The most effective method for achieving this is through selective area etching (SAE) followed by selective area growth (SAG). In this talk, we will discuss the progress made at Yale in the selective-area etching, growth, and doping of GaN.Selective-area etching of GaN is the most challenging and critical step in this process. Instead of using conventional ICP etching, we have employed tertiarybutylchloride (TBCl) as an in-situ chemical etchant of GaN in MOCVD to create smooth trenches and remove plasma etching-generated damages on the surface. With electrical and material characterizations, we have confirmed that TBCl etching is a low-damage and clean etching process. We will also describe our recent efforts to bypass the constraint of dielectric masking during in-situ etching and perform maskless selective area etching (SAE) to create low-defect lateral p-n junctions for GaN power electronics. Additionally, we will discuss non-planar selective-area growth and doping, including the principles of growth evolution, non-uniform Mg distribution, and parasitic impurities.This work is supported by the Advanced Research Projects Agency-Energy (ARPA-E), U.S. DOE, under DE-AR0000871 as part of the PNDIODES program managed by Dr. Isik Kizilyalli.