Electrical, optical and surface morphology characteristics of InP grown using a valved phosphorus cracker cell in solid source molecular beam epitaxy

Abstract

We report on the molecular beam epitaxial (MBE) growth of epitaxial InP using a valved phosphorous cracker cell at various ranges of V/III flux ratio (V/III=1.2–9.3) and substrate temperatures ( T s=360–500°C). The as-grown epitaxial InP on InP (100) substrate was found to be n-type from Hall measurements. The background electron concentration and mobility exhibited a pronounced dependence on the V/III flux ratio and substrate temperature. Using a cracking zone temperature of 850°C, the highest 77 K electron mobility of 40900 cm 2 Vs −1 was achieved at a V/III ratio of 2.3 at substrate temperature ( T s) of 440°C. The corresponding background electron concentration was 1.74×10 15 cm −3. The photoluminescence (PL) spectra showed two prominent peaks at 1.384 and 1.415 eV. The lowest PL FWHM achieved at 5 K was 5.2 meV. Within the range of substrate temperature investigated, the effect on the crystalline quality determined from X-ray diffraction (XRD) measurements was not significant. The surface morphology deteriorated following a reduction in the V/III ratio or an increase in the substrate temperature. In extremis, the formation of indium droplets and severe surface faceting occurred.