Study The Epitaxy Of AlGaN/GaN Heterostructures On Silicon Substructes

Galliμm nitride (GaN) is the fastest grown third generation of semiconductor materials in recent years. Because of the chemical properties high temperature, direct band gap is wide, high-frequency high-power GaN stability, it able to make good such as semiconductor materials, Si and AsGa. Now GaN is the next generation semiconductor material devices mainly used materials research focus at home and abroad. AlGaN/GaN based high electron mobility transistors (HEMT) is a GaN-based microwave power devices based on AlGaN/GaN. Compared with the conventional MESFET, HEMT has the outstanding performances of high trans-conductance, high output current density and high cutoff frequency. So it will become Next-generation communications industry mainly used in microwave devices.GaN materials at home and abroad have already conducted many years of research and become Start Commercial applications. Btu there are many problems to be solved now. This paper introduces the domestic and international research on materials for GaN and application prospects, and then introduced the two-step growth of GaN crystal growth. Finally we relate defect type in the GaN crystal and effect of GaN crystal.In the experiment, this paper discusses in detail the growth of GaN crystal in Si substrates with different buffer layers. And we found the value of the window of GaN with different buffer layers. We measure XRD, AFM and microscope of samples with different growth conditions. We also compared the lateral pros and cons of various buffer layer grown GaN in 2-inch Si. We found GaN epitaxial layers with Continuously AlGan/GaN buffer layer is the best in all GaN epitaxial layers with different buffer layer. Finally, we studied grown GaN epitaxial layers with super-lattice, so that wo can grown large GaN epitaxial layers in further.Next, we grow AlGaN/GaN heterojunction with AlN barrier layer. In the work we optimize thickness and composition of AlN barrier layer, and we have grown AlGaN/GaN heterojunction which crystal quality and surface morphology up to international standards.