Experimental considerations for in situ X-ray scattering analysis of OMVPE growth

We have recently performed a set of experiments using a chamber for growth of semiconductor single crystal films via organometallic vapor phase epitaxy (OMVPE) while simultaneously scattering X-rays from the growing crystal surface. Due to the special complications of OMVPE growth, such as near-atmospheric pressures, toxic and flammable gases, and high substrate temperatures, the chamber design includes many novel features. In this paper we will discuss the advantages of the z-axis diffractometer for such a chamber and the specific solutions to problems such as convective flow near the sample and film growth on the Be windows attached to the growth chamber. The X-rays enter the chamber through a 35-mm-diameter Be window mounted on a 2.75 in. UHV flange; they exit through a separate window which allows detection of X-rays from -5deg to 125deg in 2θ and take-off angles from the surface from -5deg to 45deg. Results from our experimental run on the PEP storage ring studying the growth of ZnSe on GaAs will be discussed. (orig.)