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采用同步辐射XRD极图法对低温MOCVD生长的GaN缓冲层薄膜进行了研究.极图研究表明,低温GaN 薄膜中除有正常结晶外还存在一次孪晶和二次孪晶.在χ固定为55°时的{111}φ扫描中发现了异常的Bragg衍射峰,表明GaN/GaAs(001)低温生长中孪晶现象非常明显.GaAs(001)表面上出现的{111}小面极性会在生长初期影响孪晶成核,实验结果表明孪晶更易在{111}B面即N面上成核.
Synchrotron radiation XRD polarography was used to study the GaN buffer layer grown by low temperature MOCVD.The polar diagram shows that there are first and second twins in the low temperature GaN thin film except for the normal crystallization.When χ is fixed at 55 Abnormal Bragg diffraction peaks were observed in the {111} φ scan at [°], indicating that the twins were very pronounced at low temperature growth of GaN / GaAs (001). The {111} facet polarity appearing on the GaAs (001) The early growth affects twin nucleation. The experimental results show that the twin nuclei are more easily nucleated on {111} B surface, ie N surface.