The temperature and pressure dependence of the deeply buried galliumnitride-gallium solid-liquid interface studied using in-situ high-energy surface X-ray diffraction

by Aryan E.F. de Jong (Radboud University, Nijmegen & ESRF, Grenoble)

Wednesday 24 Jun 2015, 15:00 → 16:00 Europe/Berlin

Bldg. 03, Room 107 (DESY Hamburg)

Gallium-nitride (GaN) recently attracted a lot of attention due to the award of the 2014 Nobel prize for physics for the creation of highly efficient blue LEDs. The ability to function in an efficient way is, however, coupled with crystal quality which is in turn largely related to the arrangement of atoms on the surface which determines the mass transport towards the interface during growth. However, even after 40 years of research the atomic scale arrangement of atoms during GaN growth is completely unknown. The reason is quite simple, none of the bulk growth techniques capable of producing high quality GaN is easily accessible for in-situ studies of the interface. The recent discovery of growth of GaN at pressures between 5 and 50 bar and a temperature of 800 C in a gallium-sodium mixture changed that. In this talk I will present a chamber to investigate the interface between GaN and liquid gallium in-situ which can speed up parameter optimizations tremendously. Furthermore, I will discuss the difficulties in sample preparation and present a full 3D model of the solid-liquid interface between GaN and gallium and its dependence on temperature and nitrogen pressure.