Growth Of Ⅲ-Nitrides Quantum Dots By MOCVD

InGaN quantum dots and GaN quantum dots are not only very potential for improvingefficiency and performance of emitting devices in visible and ultraviolet regions（including light emitting diode and laser diode）, but also are important materials forfabricating quantum computing unit, detector and single photon source. InGaN quantumdots are high quality material structures for realizing high efficiency solar cell.By using MOCVD （metal organic chemical vapor deposition） method,this paperexplored growth process of InGaN/GaN quantum dots and GaN/AlN quantum dots singlelayer structures, in order to control the size, shape, distribution uniformity and density ofquantum dots. Main research content is as follows:First of all, LT-AlN/HT-AlN was used as the buffer layer for the preparation of highcrystal quality GaN templates, and PALE method growth for low surface roughness andlow defect density AlN templates.Secondly the surface morphology evolution of the InGaN thin film was investigated.The islands clusters of the petals shape appeared on the InGaN thin film, which maybewas resulted from stress accumulation. And influences of the temperature, precursorsflows and other growth parameters, were researched. The temperature and TMIn flowwere found playing a key role.Then the S-K mode growth of InGaN quantum dots were studied. First, low densityInGaN quantum dots were fabricated at the higher temperature of700°C, with the densityabout4×10⁸cm^-2, average diameter76nm and average height8.5nm. Secondly, InGaNquantum dots of relatively high density were fabricated at600°C, which owned thedensity about1.6×10¹⁰cm^-2, average diameter42nm and average height4.2nm. And thenthe influences of growth temperature, NH3flow, TMIn flow, annealing （environment,temperature and time） were further studied. At last, it was found that growth interruptmethod was an effective way to control the size and density of quantum dots.Finally the growth of GaN quantum dots by droplet epitaxy method was studied,during which Ga droplets were nitrided into GaN quantum dots. Ga droplets appearredtwo sorts of size distribution. Ga droplets density is about6.3×10¹⁰cm^-2, meanwhile therange of diameter and height are respectively18-39nm and2-12nm. The influence of high temperature annealing on the GaN quantum dots was also studied, and it was foundthat size and density of GaN quantum dots were reduced after high temperature annealing.In the end, the GaN quantum dots were covered by a layer of AlGaN.