Synthesis, Doping Modification And Optical Properties Of Group-Ⅲ Mitride Nanostructures

Group-HI nitrides, represented by aluminum nitride (A1N), have outstanding performances including a direct wide band gap, high breakdown voltage, high heat conductivity, high electron saturation rate and radiation resistance, and at the same time they are physically and chemically stable. Thus they have good potential applications in the field of optoelectronics and microelectronics. A1N, GaN and InN can form multicomponent alloys with an adjustable band gap. They are essential to optoelectronic devices whose wavelength coverage deep UV to the near in&ared band. So they have been attached much attention in the area of light emitting diode (LED), laser diode (LD), and (deep) ultraviolet photodetector (PD), etc. But because of the problems in the preparation and doping efficiency, its development in optoelectronic devices is restricted. In the overall background of the rapid development of nanotechnology, group-Ill nitride low dimension nanomarterials are expected to improve the performance of materials in terms of their structure, and the basic research works are of great importance, such as preparation of group-Ill nitride nanomaterials, doping modification and performance. This paper focuses on controllable preparation and doping modification of the AlN-based group-Ill nitride nanostructures. It emphasizes the controlling of composition, structures and morphologies of these materials, and the effect of them on optical or magnetic properties of products. Main contents and conclusions are as follows:(1) With a simple thermal chemical vapor deposition (CVD) method in the absence of any template and catalyst support, series of regular morphology A1N nanostructure arrays were controllably prepared successfully. A1N nanostructures’growth behaviors follow VS growth mechanism, and can be divided into three processes including nucleation, nucleus arrangement and orientation growth, in which the density of nucleation determines the final morphology. Through further experimental analysis, it has been found that the temperature and ammonia flow were the key experiment parameters of A1N nanostructures growth process. The room-temperature PL spectra showed that the A1N hexagonal nanotubes sample has great ultraviolet emission performance.(2)Mn-doped AlN hexagonal complex nanomaze structure was prepared.It has good photoluminescence performance,and show the two emiSsion peaks at 500 nm and 600nm,which comes from complex defects of (?)ON+ and characteristic emission of Mn ion,4T1-6A1; Temperature and Mn concentration dirctly affect morphology of nanostructure and luminescent properties.Room-temperature ferromagnetism of samples relies on the Mn content.(3)Pure and Mg-doped AIN hexagonal nanorods away were prepared.Through the comparative analysis,it can be confirmed that Mg doping play an important role in growth and ultraviolet emission preformance.Mg doping not only improved the surface diflusion of adatom, which makes the AIN nanostures grow faster,but also increased the proportion of VN which affects the ultraviolet luminescence property of product.(4)The morphologies,optical and magneric properties of series Co-doped AIN nsnostrures showed obvious temperature-dependent behaviors.High temperature not only favors the incorporation of Co,but also improves the growth speed of AIN nanostructures.All samples showed two emission bands involving VN and O impurities,and strong room-temperature ferromagnetism.(5)A simple controllable preparation methods of high content Al of AlG-aN nanometer materials had been preliminary explored.Ga was designed and doped into AIN to obtain AlGaN nanomaterials.Through the discussion of the experimental parameters such as temperature and NH3 flow,optimized growth parameters of AlGaN nanostructures which possess good crystalline and luminescence performance.(6)Based on the VLS growth mechanism,two kinds of morphology of InN nanowires were prepared with gold catalysts under 500℃:Smooth nanowires and bamboo-like nanowircs.Growth direction of smooth nanowires is <1120>,while that of bamboo-like nanowires is <0001>.The difference between the growth directions of two nanowires was controlled by competition of energy of two different planes.