未掺杂GaN外延膜的结晶特性与蓝带发光关系的研究

采用卢瑟福背散射／沟道技术，X射线双晶衍射技术和光致发光技术对几个以MOCVD技术生长的蓝带发光差异明显的未掺杂GaN外延膜和GaN：Mg外延膜进行了测试。结果表明，未掺杂GaN薄膜中出现的2．9eV左右的蓝带发光与薄膜的结晶品质密切相关。随未掺杂GaN的蓝带强度与带边强度之比增大，GaN的卢瑟福背散射／沟道谱最低产额增大，X射线双晶衍射峰半高宽增大。未掺杂GaN薄膜的蓝带发光与薄膜中的某种本征缺陷有关。研究还表明，未掺杂GaN中出现的蓝带与GaN：Mg外延膜中出现的2．9eV左右的发光峰的发光机理不同。

Relationship between structure characteristic and blue luminescence in unintentional doped GaN layers

Properties of some GaN and GaN:Mg films with different blue luminescence relative intensity were investigated by Rutherford backscattermg/channeling measurement, double crystal X-ray diffraction measurement, photoluminescence technique, respectively. The blue luminescence in unintentional doped GaN layers obvious relates with the crystalline quality of those films. The RBS/channeling Xmin and the FWHM of double crystal X-ray diffraction increase with the increase of the intensity ratio of the blue luminescence to the band edge emission. The blue luminescence is due to some defects in unintentional doped GaN films. The peak position of blue luminescence in unintentional doped GaN films do not shift and its intensity superlinear increases with the growth of excitation density. These results indicate that it is the transition from the free electron to acceptor levels. The peak energy of blue luminescence about 2.88 eV in GaN:Mg films increases about 25meV and its intensity linearly increases with the growth of excitation density. These results indicate that it is the transition of donor-acceptor pair in GaN:Mg films. The mechanism of the blue luminescence in unintentional doped GaN films is different from the blue luminescence about 2.9 eV in GaN:Mg films.