ZnSe Molecular Beam Epitaxial Growth on Charge-Balanced GaAs Surfaces

ZnSe相关的II-VI宽隙半导体是光电子器件中很有前途的材料。为了获得理想的没有电荷不平衡的ZnSe/GaAs界面，我们利用反射高能电子衍射（RHEED）、原子力显微镜（AFM）、光致发光（PL）、透射电子显微镜、高分辨率x射线衍射和PL形貌研究了分子束外延在邻近的GaAs（110）衬底上生长的ZnSe外延层。相邻GaAs（110）表面的ZnSe薄膜向（111）A方向取向6°，晶体质量差，表面形貌粗糙。另一方面，RHEED和AFM观察显示，ZnSe在相邻的GaAs（110）表面上以一层接一层的方式生长，这些表面向（111）B取向6°，并且由单原子台阶的规则阵列组成。PL光谱以近带边发射为主。然而，观察到层错的特征结构和高密度的螺纹位错。通过添加GaAs缓冲层，我们成功地将这些堆叠错误和线程位错降低到两到三阶以下。具有高质量和平坦界面的ZnSe（110）薄膜在相邻的GaAs（110）表面上相干生长，GaAs（110）表面向（111）B倾斜6°，具有GaAs缓冲层。

ZnSe related II-VI widegap semiconductors are promising materials for optoelectronic devices. In order to obtain ideal ZnSe/GaAs interfaces without the charge imbalance, we have investigated ZnSe epitaxial layers grown by molecular beam epitaxy on vicinal GaAs (110) substrates using reflection high-energy electron diffraction (RHEED), atomic force microscopy (AFM), photoluminescence (PL), transmission electron microscopy, high-resolution X-ray diffraction, and PL topography.ZnSe films on vicinal GaAs (110) surfaces misoriented 6° toward (111) A show poor crystal quality and rough surface morphology with (111) facets. On the other hand, RHEED and AFM observations reveal that ZnSe growth proceeds in a layer-by-layer fashion on vicinal GaAs (110) surfaces misoriented 6° toward (111) B and that the surfaces consist of regular arrays of monoatomic steps. The PL spectra are dominated by the near-band-edge emission. However, characteristic structures of stacking faults and high density of threading dislocations are observed. We successfully decreased these stacking faults and threading dislocations lower than two or three orders by incorporating GaAs buffer layers. ZnSe (110) films with high-quality and flat interfaces are coherently grown on vicinal GaAs (110) surfaces misoriented 6° towards (111) B with GaAs buffer layers.