Studies on MOVPE growth of GaP epitaxial layer on Si(0Â 0Â 1) substrate and effects of annealing

Growth of gallium phosphide layer on silicon substrate has been carried out using metal-organic vapor phase epitaxy. Epitaxial layers were grown at 845 °C with a V/III ratio of 100 and a growth rate of 1.7 Å s−1at a reactor pressure of 30 mbar. The nominal thickness of the gallium phosphide epitaxial layer is ∼600 nm as measured by cross-sectional scanning electron microscopy. Growth of gallium phosphide epilayer is confirmed by Raman spectra studies. High-resolution X-ray diffraction studies show that the epilayer is of single crystalline nature and structurally coherent with silicon substrate. It is also inferred from these measurements that the in- and out of plane strain arising from small mismatch confirms a relaxed epilayer. As-grown epilayer shows p-type behavior with a hole carrier density of ∼1.2×1018cm−3 and hole mobility 114 cm−2V s−1 at room temperature. Annealing at 550 °C for 10 min shows significant improvements in crystalline quality of the epilayer. The annealed layer shows a reduced hole density (∼6.7×1017cm−3) and increased hole mobility (155 cm−2 V s−1).