Study Of Laser Molecular Beam Epitaxy Of Cubic MgZnO Thin Films And Physical Properties

In the past two decades, Mg Zn O alloy materials have attracted more and more attention for their potential applications in military and industry. As a wide band gap semiconductor materials for UV(380-260nm) emitting and detection, it’s very important to improve the crystalline quality of Mg Zn O epilayer. However the structure of MgxZn1-xO is a mixed phase when x in the range of 30%~60%. It is in wurtzite structure when x less then 30% and in rock-salt structure when x more then 60%. So it’s difficult to prepare a single-phase thin film of Mg Zn O when 30%<x<60%. In this paper, we attempted to prepare Mg Zn O film with single cubic structure by laser molecular beam epitaxy(LMBE) techniques for the solar-blind UV detection(<280nm). The main contents are as follows:(1) Mg Zn O films were grown by LMBE on the sapphire substrate with different orientations(c-,m-,r-,a-). It was found that the orientation of Mg Zn O epitaxial films will follow the surface atomic arrangement of the sapphire substrates. By comparing the experimental datas with the calculated d spaces and the lattice constants of Mg Zn O films, the structure and physical properties of Mg Zn O films were discussed in terms of the lattice mismatch and the internal stress.(2) Single-phase cubic structure Mg Zn O thin films were prepared successfully on the Mg O(200) substrate. The internal stress of Mg Zn O is calculated to be greater than the wurtzite to cubic phase tranition pressure, which is the reason for formation of cubic Mg Zn O. Then,the built-up and release of stress in Zn O epilayer were monitored by observing the evolution of RHEED patterns during the LMBE grown of Zn O on the Mg O(200) substrate. Finally, we have tried to prepare multilayer structures of Mg Zn O/Mg O by LMBE. This work will provide experimental basis for the future working on solar bind detectors.