Micro-Raman analysis of molar fraction in polycrystalline In_xGa_1-x for traveling liquidus zone growth method

摘要

In_xGa_1-xAs is a tunable lattice matched bulksubstrate material for fabricating InGaAs-based optoelectronic devices.Spatial homogeneity in molar fraction for such substrates is essential.It is planned to grow compositionally homogeneousIn_xGa_1-xAs bulk substrate using In_xGa_1-xAs polycrystals with graded molar fraction profile as thestarting material in the traveling liquidus zone growth method. Toanalyze these starting materials, particularly the molar fraction,non-destructive techniques are essential. In this paper, we report someresults on micro-Raman studies in these polycrystalline startingmaterials with various values of molar fraction, and a polycrystallineIn_xGa_1-xAs cylindrical sample with graded molarfraction profile. Estimated molar fraction using Raman scattering forvarious polycrystalline samples show good agreements with those examinedby chemical analysis. We further report the effect of surface conditionon our results, using micro-Raman technique