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

为了阐明InAlGaN合金半导体的成分不均匀性，在(0001)取向的蓝宝石衬底上生长了不同In组分的GaN外延层。用X射线衍射法、光吸收法、光电导法和阴极发光法对样品的组成不均匀性进行了研究。结果表明：1)In组分相对较低时，In与Tmin气相组分成正比，但当In组分超过0.2时，In与Tmin气相组分成正比。2)X射线衍射测量表明，In组分超过0.2时，(0002)和(30-30)衍射峰的线宽都变宽，衍射峰在低衍射侧显示较大的尾部，这意味着In组分在AlN层中分散较大。3)从光电导测量中观察到3.3 eV和3.6 eV处有两个额外的结构，4)从化学发光测量来看，AlInN层有两个主要的发光峰，分别位于3.0 eV和3.8 eV处，这与In的组成有关。

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.