Influence of methane concentration on MPCVD overgrowth of 100-oriented etched diamond substrates

Abstract

Selective diamond growth on etched diamond substrates allows the development of 3D-type device geometries, which can make possible higher capacity, higher surface for contacts and benefits from better properties versus growth orientation. Such structures need the control of lateral growth or lateral etching that guarantee the best epitaxial growth, with a well-faceted surface, with a minimum density of emerging defects in order to limit the current leakage and to improve the breakdown voltage. Previous works used 111-oriented selective growth on etched diamond for lateral p–n junctions or bipolar junction transistors. The behavior of homoepitaxial overgrowth on etched diamond substrates depends directly on growth parameters such as temperature, gas concentration or microwave power that can favor the growth in one specific direction. The present contribution considers the effect of methane concentration during the overgrowth of the mesa pattern. The presence of highly doped intermediate layers allowed following the growth plane orientation in a stratigraphic approach. Faceting and growth velocities were analyzed using scanning and transmission electron microscopes (SEM and TEM).