Molecular Beam Epitaxial Growth of InP Using a Valved Phosphorus Cracker Cell: Optimization of Electrical, Optical and Surface Morphology Characteristics

Abstract

We report the molecular beam epitaxial (MBE) growth of epitaxial InP using a valved phosphorous cracker cell at a range of cracking zone temperature (Tcr=875°C to 950°C), V/III flux ratio (V/III=1.2 to 9.3) and substrate temperature (Ts=360°C to 500°C). From Hall measurements, the as-grown epitaxial InP on InP (100) substrate was found to be n-type. The background electron concentration and mobility exhibited a pronounced dependence on the cracking zone temperature, V/III flux ratio and substrate temperature. Using a cracking zone temperature of 850°C, the highest 77 K electron mobility of 40900 cm2/Vs was achieved at a V/III ratio of 2.3 at a substrate temperature (Ts) of 440°C. The corresponding background electron concentration was 1.74×1015 cm-3. The photoluminescence (PL) spectra showed two prominent peaks at 1.384 eV and 1.415 eV, with the intensity of the low-energy peak becoming stronger at higher cracking zone temperatures. The surface morphology deteriorated following a reduction in the V/III ratio or an increase in the substrate temperature. In the extreme case, formation of free indium droplets and severe surface faceting occurred.