Optimisation of InP growth by molecular beam epitaxy using a valve phosphorus cracker cell

Abstract

We report the molecular beam epitaxial (MBE) growth of epitaxial InP using a valve phosphorous cracker cell over a range of cracking zone temperatures ( T cr=875°C to 950°C), V/III flux ratios (V/III=1.2 to 9.3) and substrate temperatures ( T s=360°C to 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 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 40 900 cm 2/Vs 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 eV and 1.415 eV, with the intensity of the low energy peak becoming stronger at higher cracking zone temperatures. The PL full-width at half maximum (FWHM) was significantly reduced as the V/III ratio was lowered, indicating an improvement in the optical quality of the samples. The lowest PL FWHM achieved at 5 K was 6.3 meV.