Phosphorus-species-induced band-gap anomaly in InGaP grown by solid-sourcemolecular-beam epitaxy

We report on the growth of InGaP by solid-source molecular-beam epitaxy. It is revealed by photoluminescence (PL) that a lower effective band-gap ener gy appeared when a higher phosphorus cracker temperature was used. Temperat ure-dependent PL and polarized photoreflectance (PR) also exhibited a weake r atomic ordering effect when the phosphorus cracker temperature increased. Since the variation of the phosphorus cracker temperature significantly ch anged the P-2/P-4 ratio, we believe that a more chemically reactive P-2 wil l not only incorporate more In atoms into the epilayer, but will also bring about a smaller composition fluctuation and weaker ordering effect. Theref ore, InGaP grown under a more P-2-rich condition probably has a higher In c ontent which results in a lower band-gap energy instead of the ordering eff ect.