The role of transient surface morphology on composition control in AlGaN layers and wells
Abstract
The mechanisms governing “compositional pulling” during the growth of AlxGa1−xN wells are investigated. Gallium-rich AlxGa1−xN wells grown on high dislocation density AlN/sapphire templates exhibit asymmetric and diffuse composition profiles, while those grown on low dislocation density native AlN substrates do not. Furthermore, strain in all AlxGa1−xN wells is found to be pseudomorphic, ruling it out as the dominating driving force. Rather, the high threading dislocation density of the AlN template is considered to play the defining role. We propose that a transient surface morphology is introduced during dislocation mediated spiral growth, which, in conjunction with process supersaturation, determines the Ga incorporation. These findings provide insights into compositional pulling in high Ga content AlxGa1−xN grown on AlN and provide a route to grow thicker wells with very abrupt interfaces on native AlN substrates.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jan 21, 2019
- Source ID
- 10.1063/1.5063933
Entities
People
- J. Houston Dycus
- James M. LeBeau
- Ramón Collazo
- Ronny Kirste
- Seiji Mita
- Shun Washiyama
- Tim B. Eldred
- Yan Guan
- Zlatko Sitar
Organizations
- Air Force Office of Scientific Research
- Army Research Office
- National Science Foundation
- North Carolina State University
- Office of Naval Research Global
- United States Department of Energy