Morphological studies of III-V thin layers and SLS'S

Thin layers of III-V semiconductors, such as quantum well structures and strained layer superlattices (SLS's), are currently of great interest. However, there have been widely scattered reports suggesting that thin layers and SLS's with arbitrarily large strain and thicknesses are difficult if not impossible to grow. In this work we studied the nucleation, morphology and structural perfection of a wide variety of thin layers in the GaAs/GalnAsP system. These epitaxial layers were grown by atmospheric pressure MOCVD. The GaAs/GalnAs system is mismatched through the entire compositional range, the extreme mismatch being 7% for GaAs/lnAs. The nucleation and growth morphology of GalnAs layers on GaAs were observed to be very strongly dependent on the mismatch (i.e. the In concentration x) This is clearly depicted in Fig. 1 which shows secondary electron micrographs of the surface of three GalnAs layers grown for 30 sec. using the same growth rate of 600 Å min-1.