Step-free GaN surfaces grown by confined-area metal-organic vapor phase epitaxy

Jon F. Ihlefeld,Isaac Bryan,Edward Sachet,Elizabeth A. Paisley,Zlatko Sitar,Ramón Collazo,Jon-Paul Maria,Nick Lavrik,Christopher T. Shelton

doi:10.1063/1.4993840

Abstract

A two-step homoepitaxial growth process producing step-free surfaces on low dislocation density, Ga-polar ammonothermal GaN single crystals is described. Growth is conducted under very low supersaturation conditions where adatom incorporation occurs predominantly at step edges, and lateral growth is strongly preferred. The achievable step-free area is limited by the substrate dislocation density. For ammonothermal crystals with an average dislocation density of ∼1 × 104 cm−2, step-free mesas up to 200 × 200 μm2 in size are achieved. These remarkable surfaces create a unique opportunity to study the effect of steps on the properties and performance of semiconductor heterostructures.

Highlights

Engineered substrate vicinality is an important innovation in semiconductor heteroepitaxy
The crystal growth formalism of Burton, Cabrera, and Frank teaches that crystals grow by a screw-dislocation mediated mechanism if such defects are present and that each screw dislocation that threads to the crystal surface is a permanent source of new steps.[13]
While this flattening process is possible in GaN, the maximum lateral area is a strict function of the screw dislocation density

Summary

Introduction

Engineered substrate vicinality is an important innovation in semiconductor heteroepitaxy. Step-free GaN surfaces grown by confined-area metal-organic vapor phase epitaxy

Results

Conclusion