Atomic layer epitaxy of ZnSe using reflectance difference spectroscopy

We applied reflectance difference (RD) spectroscopy to the atomic layer epitaxy (ALE) of ZnSe and proved the self-limiting process of Se atoms by means of in-situ monitoring of the RD intensity. The ALE of ZnSe was performed on a ZnSe buffer layer grown on a GaAs substrate at 275°C. During the ALE growth with the alternate molecular beam supply of Zn and Se atoms, the intensity of the RD signal at 4.2 eV showed a cyclic change between the Zn level and the Se level, respectively. Furthermore, the Se level was found to stay constant both after the pulsed supply of Se atoms and during the continuous supply of Se atoms, while the intensity recovered from the Zn level to the Se level exponentially after the pulsed supply of Zn atoms. These facts show that the self-limiting mechanism prevails only in the atomic layer formation of Se on the ZnSe outermost surface.