The Preparation And Growth Technology Of MgZnO Quasi-ternary Alloys

In recent years,GaN and ZnO,as the third generation semiconductor materials,are more and more noticed by researchers with the development of wide band gap semiconductor industry.GaN has been used in the field of new-type photoelectric devices.ZnO has larger exciton binding energy(60meV in room temperature)compared to GaN.So the application prospect of ZnO in the field of ultravoilet and deep ultravoilet are broad.As a member of ZnO-based materials,MgZnO material has a lot of unique advantages.The band gap of MgZnO material can be tuned by adjusting the Mg/Zn ratio.It promotes the development of ZnO-based materials further in the field of ultraviolet and deep ultraviolet.It is very important to grow high-quality ZnO-based materials for the fabrication of high-quality ZnO-based semiconductor devices.In this paper,MgZnO quasi-ternary alloys were grown by molecular beam epitaxy(MBE).The effects of different growth techniques on the crystal quality,surface morphology and optical properties of MgZnO quasi-ternary alloys were investigated by changing the treatment techniques,oxygen partial pressure and buffer layer in the process of growth.The surface morphology,crystal quality and optical properties of the samples were measured by X-ray diffraction(XRD),atomic force microscopy(AFM),transmission spectrum and photoluminescence(PL).By changing the oxygen partial pressure of the MgZnO layer during growth,we found that lower oxygen partial pressure can optimize the crystal quality and influence the surface morphology of the samples.We investigated the effects of different buffer layers on the epitaxial MgZnO alloy by annealing MgO buffer layer in zinc(Zn)or oxygen(O)atmosphere.The XRD and AFM showed that the surface morphology and crystal quality of the samples annealed in Zn atmosphere were obviously improved.The transmission spectrum also proved this point.When a layer of ZnO buffer layer is inserted between the MgO buffer layer and the epitaxial MgZnO quasi-ternary alloy,the crystal quality and surface roughness of the samples were decreased.And there is no obvious difference in the crystal quality and surface morphology between the samples caused by Zn treatment and O treatment.It can be an important experimental reference for the growth of high quality MgZnO alloys on thin buffer layers.In addition,the XRD and AFM showed that the Mg component of the epitaxial MgZnO quasi-ternary alloy was increased obviously in the samples whose buffer layer were annealed in Zn atmosphere,indicating that the Zn treatment of the buffer layer could have enhanced the adsorption of Mg atoms in a certain degree.And when a layer of ZnO buffer layer is added,such a difference will be more obviously.The Zn treatment method can adjust the Mg component of MgZno quasi-ternary alloys.