Influence of growth conditions on tin incorporation in GaAs grown by molecular beam epitaxy

• Published in: Journal of applied physics 1980-08, Vol.51 (8), p.4296-4304
• Main Authors: Alexandre, F., Raisin, C., Abdalla, M. I., Brenac, A., Masson, J. M.
• Format: Article
• Language: English
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.328248

Intentional perturbations applied to the growth parameters of Sn-doped GaAs layers grown by molecular beam epitaxy have been performed in order to investigate the tin incorporation mechanism. The start, the interruption, and the end of growth as well as a variation of fluxes or substrate temperature have been studied, using either the Auger electron spectroscopy (AES) measurement of tin accumulation on the surface, or C-V derived free-carrier concentration profile versus any of these growth parameters. The theoretical model proposed by Wood and Joyce, based on a time-delayed incorporation mechanism, has been found to fit the observed results, especially for As-rich surface, provided that an incorporation mechanism of second order is assumed. For Ga-rich conditions (Ts≳580 °C), a new result has been recognized, i.e., a significant reduction of carrier concentration as Ts is increased. The assumption of a partially acceptor nature of tin incident atoms under these growth conditions does not seem to fully explain this result. On the other hand, this may be better understood assuming a certain amount of tin atoms being re-evaporated in the high substrate temperature range. This behavior induces a temporarily weaker accumulation at the surface, and hence a relatively smaller incorporation rate.