Investigation of Compositional Inhomogeneity in InAlGaN and Realization of Lattice-Matched Quantum Structure by Group-III Nitrides

为了阐明InAlGaN合金半导体中的成分不均匀性，在（0001）取向的蓝宝石衬底GaN外延层上生长了不同In成分的AlInN层。通过X射线衍射、光吸收、光电导和阴极发光测量研究了组成的不均匀性。结果表明：（1）In的固体成分与TMIn的蒸气成分成正比，但当In的组分超过0.2时，固体成分趋于饱和;（2）XRD测量表明，当In的组分超过0.2时，（0002）和（30-30）衍射线的线宽都变宽，并且衍射峰在低衍射侧显示出大的拖尾，这意味着AlInN层中In组分的大的分散。3）从光电导测量中，在3.3eV和3.6eV处观察到两个额外的结构，这表明该层由具有不同In组分的至少两种畴组成。4）从CL测量中，观察到来自AlInN层的两个主要发光峰在3.0eV和3.8eV处，并且取决于In组分。

In order to clarify the compositional inhomogeneity in InAlGaN alloy semiconductor, AlInN layers with various In composition have been grown on GaN epilayer on (0001) oriented sapphire substrate. The composition inhomogeneity was investigated by x-ray diffraction, optical absorption, photoconductivity, and cathodoluminescence measurements. Obtained results are summarized as follows,1) In solid composition is proportional to the TMIn vapor composition for relatively low In composition, but seems to saturate when the In composition exceeds 0.2.2) XRD measurements show that the both the linewidth of (0002) and (30-30) diffractions become wider when the In composition exceeds 0.2, and the diffraction peak indicates large tail in low diffraction side meaning the large dispersion of In composition in the AlInN layer.3) From the photoconductivity measurement, two additional structures are observed at 3.3eV and 3.6eV, suggesting that the layer composed of the at least two kinds of domains with different In composition.4) From the CL measurements, there are two major luminescence peaks from AlInN layers are observed at 3.0eV and 3.8eV and dependent on the In composition.