Hot-Wall MOCVD for High-Quality Homoepitaxy of GaN: Understanding Nucleation and Design of Growth Strategies

Abstract

Thick GaN layers with a low concentration of defects are the key to enable next-generation vertical power electronic devices. Here, we explore hot-wall metalorganic chemical vapor deposition (MOCVD) for the development of GaN homoepitaxy. We propose a new approach to grow high-quality homoepitaxial GaN in N2-rich carrier gas and at a higher supersaturation as compared to heteroepitaxy. We develop a low-temperature GaN as an optimum nucleation scheme based on the evolution and thermal stability of the GaN surface under different gas compositions and temperatures. Analysis in the framework of nucleation theory of homoepitaxial layers simultaneously grown on GaN templates on SiC and on hydride vapor phase epitaxy GaN substrates is presented. We show that residual strain and screw dislocation densities affect GaN nucleation and subsequent growth leading to distinctively different morphologies of GaN homoepitaxial layers grown on GaN templates and native substrates, respectively. The established comprehensive picture provides a guidance for designing strategies for growth conditions optimization in GaN homoepitaxy. GaN with atomically flat and smooth epilayer surfaces with a root-mean-square roughness value as low as 0.049 nm and low background carbon concentration of 5.3 × 1015 cm–3 has been achieved. It is also shown that there is no generation of additional dislocations during homoepitaxial growth. Thus, our results demonstrate the potential of the hot-wall MOCVD technique to deliver high-quality GaN material for vertical power devices.

III-Nitride Magnetron Sputter Epitaxy on Si: Controlling Morphology, Crystal Quality, and Polarity Using Al Seed Layers

“…Extensive research efforts dedicated to III-nitride semiconductors have led to the broad integration of GaN and AlN in contemporary optoelectronic and power electronic devices. − Established growth methods for III-nitrides, such as metal–organic chemical vapor phase epitaxy (MOVPE), provide high-quality films; however, they rely on high growth temperatures and expensive precursors. − In recent years, there has been an increasing focus on exploring alternative growth techniques to enable cost-effective and high-quality manufacturing of electronic devices for widespread applications. Magnetron sputter epitaxy (MSE) is an emerging technology that offers many advantages for device-quality III-nitride growth: cost-effectiveness, high-throughput, and ease of scalability.…”

Research progress and prospect of GaN Schottky diodes

“…Therefore, this is a balancing process. In addition, the GaN homogeneous epitaxy technology is not mature [17], with high cost and large trap state density. Therefore, the trapped electron in GaN layer is caused by both thermionic emission and trap assisted tunneling, which can increase the leakage current of vertical GaN-based diodes, and the breakdown voltage is limited [18].…”