Optical and structural characterization of single quantum wells of InGaAs on GaAs MOCVD grown both on exactly oriented and misoriented substrates

The quality of strained single quantum wells (SQWs) of InxGa1-xAs with different thicknesses and In compositions grown by LP-MOCVD on exactly (100) oriented and (100) 2 degrees off [110] oriented GaAs substrates has been investigated. All these samples were investigated by means of High Resolution X-Ray Diffraction (HR-XRD), Room and Low Temperature Photoluminescence (RT FL, LT FL) and Transmission Electron Microscopy (TEM). We have clear evidence that the quality of the SQWs grown on exactly oriented substrates is markedly superior with respect to those grown on misoriented substrates. The LT PL measurements are supported by the TEM characterization: the SQWs with In composition 0.22 grown on miscut substrates are seen to grow in macrosteps which are absent in the (100) substrates. In segregation towards the upper edge of each individual macrostep has been observed. The following micro non-uniformities in the In content inside the wells reflect in the PL FWHM behaviour for varying thicknesses. For In below 0.20 the macrostep coupled to In segregation is absent indicating a dependence on strain of this phenomenon.