MBE growth, processing and stability of zinc blende MgS based heterostructures

Abstract

This thesis investigates the MBE growth, stability and processing of zinc blende (ZB) MgS based structures. Although MgS has already proven effective in several applications, its growth in the ZB phase is still restricted due to a variety of reasons. Therefore, the main emphasis of this thesis is on probing the growth related problems and developing new growth techniques. A new method to control the formation of surface defects which causes the rapid oxidation of MgS layers has been developed first. In contrast to theoretical predictions, the growth of ZB MgS has been successfully demonstrated on GaP, together with GaAs and InP. The Epitaxial Lift-off (ELO) of deposited layers was successfully demonstrated on all three substrates. A new modification to the existing ELO technique, by using polyurethane based flexible carriers, which eliminates the use of wax and thus avoids many associated problems, has been demonstrated and a simple sample passivation method based on amorphous selenium is also explained. An effective method to reduce the number of quantum dots by introducing time delays at various stages of the growth is developed. Finally, the first experimental demonstration of the direct growth of ZB MgS on GaAs substrate is followed by the application of this result in reusable substrates. A single GaAs substrate has been reused five times while still maintaining the epilayer quality, by performing ELO.