Growth and in situ monitoring of GaN using IR interference effects

Previously we have reported the MOVPE growth of GaN and related materials o n (0 0 0 1) sapphire in a close-spaced vertical rotating disk reactor (W. V an der Stricht et al., J. Crystal Growth 170 (1997) 344). In this paper we describe the in situ monitoring of this growth process by infra-red (IR) ra diation interferometry using a fiber coupled optical pyrometer. During grow th the amplitude of the IR radiation, emanating from the susceptor (transmi tted through the substrate and growing layer) exhibits oscillations which a s Nakamura (Jpn. J. Appl. Phys. 30 (1991) 1620) has shown, can be used for monitoring GaN deposition. The form of these oscillations can give an insig ht into the progress of the growth, allowing the effects of a number of gro wth parameters to be tracked in real time. We will also describe a simple c omputer model which simulates these oscillations and we show how IR radiati on interferometry has been used to monitor growth in a close-spaced vertica l rotating disk reactor. Specifically we have studied the effects on morpho logy and growth rate of parameters such as reactor pressure, nucleation lay er growth and overlayer growth temperature. (C) 1998 Elsevier Science B.V. All rights reserved.