Research On The Synthesis Of One-Dimensional Mg-doping GaN Nanowires Using Au As Catalyst

Nanowires,nanobelts,and nanorods are a new type of one-dimensional materials which have been attracting a great deal of research interest in the past few years.It was announced that nanowires and nano-circuit will be a major breakthrough by《Science》in 2001.According to the latest articles in Nature,nanowires,nanorod and naobelts should be considered as an important part in the research of nanotechnology in any case.It is no double that nanowire will play an important role in the research in the next ten years.Due to the applications in the blue LED and high-speed electronic devices,amounts of research has been done about the synthesis of nano-structures and devices,such as nanowires,nanorods and so on and a large amount of them has been reported about the new method and material.The band gap transitions of GaN is in the ultraviolet region.Due to the doping of different kinds of impurities,its optical wavelength will move into the visual region. GaN has predominance advantage in this field,especially in blue light materials.In recent years,there is a great improvement in the synthesis of materials and preparation of device.The successful development of LED and LD contributed to the development of GaN nanowires.At present,the handicaps in the development of GaN nanowires is mainly of the high background carrier concentration and the lower p-type doping level.Background carrier concentration may link with N vacant, substitution diffusion Si,substitution diffusion O and so on.About the P-type doping, accept Mg is compensated by H,which make GaN become semi-insulate.By the treatment of LEEBI or RTA,part of Mg will be activated and the concentration of carrier vacancy can reach to 10¹⁸cm^-3.But it is also meet the need of preparation of electronic devices,which may due to the higher ionization energy of Mg.Some other doping impurities are also under research.However,the report of Mg-doping GaN nanowires is seldom seen.In this paper,one-dimensional nanostructures GaN were prepared through magnetron sputtering and ammoniating process using Mg as doping materials on Si (111) substrates.The morphology,microstructure,and components of nanostructures were analyzed through scanning electron microscopy(SEM),transmission electron microscopy(TEM),high resolution transmission electron microscopy(HRTEM), X-ray diffraction(XRD),Fourier transformed infrared spectra(FTIR) and X-ray photoelectron spectra(XPS) and so on.We also have a brief discussion about the growth mechanism of GaN nanostructures.The effects on GaN nanostructures were discussed on various experimental conditions such as the mass of Mg,ammoniating temperature and ammoniating time and so on.Firstly,Ga₂O₃/Au film is deposited on Si(111) substrates by magnetron sputtering system,and then Mg-doping GaN nanostructures were fabricated through ammoniating.The results of these experiments indicated that the as-synthesized GaN nanostructures were hexagonal GaN with wurtzite structure.The crystalline quality and morphology of GaN nanostructures were greatly influenced by the ammoniating temperature,ammoniating time and the mass of Mg.With the increase of temperature, some grain-shaped crystals were formed firstly,and then the diameter of GaN nanowires increased and became to be relatively smooth.The crystalline quality of these GaN nanostructures was also improved.The samples annealed at 900℃exhibited the best crystal quality and morphology.But the crystalline quality felled and the amount of these GaN nanostructures decreased when the temperature reached to(above 950℃).We can get the best results by ammoniating for 10min.A VLS mechanism was possible valid in the growth process of GaN nanostructures in this method.The Au film broke up,and then the liquid Au nanodroplets which act as energetically favorable sites for absorption of gas-phase reactants are formed on the Si surface at high temperature,which may plays an important role in the formation of Mg-doped GaN nanostructures.