CAJ | 학술논문

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}ψ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.
채용동보복사XRD겁도법대저온MOCVD생장적GaN완충층박막진행료연구.겁도연구표명,저온GaN박막중제유정상결정외환존재일차련정화이차련정.재χ고정위55°시적{111}ψ소묘중발현료이상적Bragg연사봉,표명GaN/GaAs(001)저온생장중련정현상비상명현.GaAs(001)표면상출현적{111}소면겁성회재생장초기영향련정성핵,실험결과표명련정경역재{111}B면즉N면상성핵.
GaN buffer layers (thickness ～60nm) grown on GaAs(001) by low-temperature MOCVD are investigated by X-ray diffraction pole figure measurements using synchrotron radiation in order to understand the heteroepitaxial growth features of GaN on GaAs(001) substrates. In addition to the epitaxially aligned crystallites,their corresponding twins of the first and the second order are found in the X-ray diffraction pole figures. Moreover, { 111 } q scans with χ at 55° reveal the abnormal distribution of Bragg diffractions. The extra intensity maxima in the pole fig ures shows that the process of twinning plays a dominating role during the growth process. It is suggested that the polarity of { 111 } facets emerged on (001) surface will affect the growth-twin nucleation at the initial stages of GaN growth on GaAs(001) substrates. It is proposed that twinning is prone to occurring on { 111 } B, N-terminated facets.