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Growth And P-type Doping Property Of GaN By RF Plasma Molecular Beam Epitaxy

Posted on:2007-06-17Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y P SuiFull Text:PDF
GTID:1118360185492333Subject:Microelectronics and Solid State Electronics
Abstract/Summary:PDF Full Text Request
Material quality and doping property of GaN-based nitrides are crucial for a host of optoelectronic and electronic device applications. This dissertation mainly focused on the growth and characterization of unintentionally doped GaN and Mg doped GaN by RF plasma-assisted molecular beam epitaxy (RF-plasma MBE). The main results achieved in this work are summarized as follows.By optimizing the growth parameters such as surface polish by Ga beam, high temperature nitridation, and low temperature buffer layer, the GaN films were grown successfully in 3D-nucleation and 2D-growth mode. The best FWHM of XRD is 560arcsec and the typical value is about 700arcsec for GaN epi-layers.The effect of III/V flux ratio on GaN growth was investigated. Based on the study of microstructure and surface morphology, it was found that the quality of the GaN epi-layer is better when it was grown under a slight Ga-rich condition. The optical property of GaN with varied III/V flux ratio was studied through photoluminescence (PL). The blue and yellow luminescence was observed at 10K and room temperature. The FWHM of exciton peak in Ga-rich GaN is narrower than that in N-rich GaN. The yellow luminescence from Ga-rich GaN was also observed which can be related to the defects (VN and VGa) existing in the material.The Mg-doped GaN epi-layers were grown by RF plasma MBE under different conditions including the Mg cell temperature, III/V flux ratio and growth temperature. By PL and Hall measurements the behavior of Mg in GaN was investigated systematically. The emission of donor-acceptor pair (DAP) was observed within the samples of lower Mg-doping temperature. In the higher-temperature Mg-doped samples, the yellow luminescence and quenching phenomena of DAP emission were observed. With the III/V flux ratio increased, the DAP peaks moved to higher energy. The hole concentration was increased with increasing both the III/V flux ratio and growth temperature. It was proposed that the YL in highly Mg-doped GaN could be attributed to the self-compensation effect...
Keywords/Search Tags:GaN, RF plasma MBE, III/V ratio, Mg doping, photoluminescence
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