Study On Growth And Characteristics Of InGaN, InN And Related Heterostructure Materials

InN and InGaN alloy possess promising application. However, as the result of the special difficulties in growth for InN and specific problems like phrase separation for InGaN, it is hard to fabricate the high quality InN-based materials. Recently, the technical progress of fabricating nitride compounds and the deepened recognition of the growth mechanism have laid a good foundation to obtain the InN-based materials of high quality and high In content. The main research of this paper focused on InN-based materials and characteristics. The main results in the paper are as follows:Through the optimization of the growth process, different In content InGaN films were grown successfully by MOCVD. The influences from growth parameters on the properties were analyzed.Based on the growth conditions of GaN, raising the pressure and reducing the temperature could increase the In content and benefit the surface morphology. Under the high pressure, the two typical surface features, pits and hillocks, were seen. When increasing the V/III ratio of reaction gases, the density and size of pits both declined. When increasing the growth temperature, the growth rate was promoted and the migration of atoms was improved and the surface was also better, at the cost of In content in the InGaN alloy.The InGaN materail was introduced into the GaN heterostructure. Through the optimization of growth parameters and structure designing, the heterostructures with InGaN channel, and the double heterostructure with InGaN back barrier were fabricated by MOCVD.For the InGaN channel, it was found that the electrical properties of 2DEG were improved under the low temperature barrier, benefited from the reduction of RMS that resulted in the promotion of mobility. And the low quality and the fluctuations of In content and thickness in InGaN channel play important roles in scattering mechanism of 2DEG. For the InGaN barrier, the confinement and the density were both raised. But the Hall mobility reduced resulting from all kinds of scatterings from the low quality of InGaN back barrier.The InN material was tried to be grown by MOCVD on different substrates and under different nitridation condition.For the sapphire substrates, it is benifical to form even and smooth hexagonal single phrase crystal structure islands if the nitridation is at high temperature. On the contrary, the low temperature nitridation is beneficial to the nucleation of InN. The shape of these islands was anomalous and their size is out of informality but bigger than that on the sapphire. On the GaN buffer, the three different crystal directions influence the surface morphology greatly.