Molecular beam epitaxial growth of InP using a valved phosphorus cracker cell: Optimization of electrical, optical and surface morphology characteristics

We report the molecular beam epitaxial (MBE) growth of epitaxial InP using a valved phosphorous cracker cell at a range of cracking zone temperature ( T-cr = 875 degrees C to 950 degrees C), V/III flux ratio (V/III=1.2 to 9.3) and substrate temperature (T-s = 360 degrees C to 500 degrees C). From Hal l 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 degree s C, the highest 77 K electron mobility of 40900 cm(2)/Vs was achieved at a V/III ratio of 2.3 at a substrate temperature (T-s) of 440 degrees C. The corresponding background electron concentration was 1.74 x 10(15) cm(-3). T he photoluminescence (PL) spectra showed two prominent peaks at 1.384 eV an d 1.415 eV, with the intensity of the low-energy peak becoming stronger at higher cracking zone temperatures. The surface morphology deteriorated foll owing a reduction in the V/III ratio or an increase in the substrate temper ature. In the extreme case, formation of free indium droplets and severe su rface faceting occurred.