a1 Materials Science Center, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083, P.R. China
a2 Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083, P.R. China
The influence of pressure on the MOCVD grown InAlN/AlN/GaN heterostructure has been investigated by high-resolution X-ray diffraction, Hall measurement and atomic force microscopy. High pressure is beneficial to increase indium incorporation efficiency. The electrical properties of InAlN/AlN/GaN heterostructure become better with the pressure decreasing from 100 Torr to 50 Torr. Indium droplets tend to form on the InAlN surface at high pressure. The edge of the indium droplet is the Al-rich region while the interior is the In-rich region, demonstrated by the phase-contrast mode. Phase contrast across the V-defect is strong on the surface of InAlN grown at low pressure (50 Torr) whereas it is not evident at high pressure (100 Torr), indicating that large stress in the InAlN film will enhance the compositional variation.
(Received October 29 2011)
(Revised December 28 2011)
(Accepted February 09 2012)
(Online publication March 01 2012)