Growth of high quality GaN layers with AlN buffer on Si(1 1 1) substrates

Abstract

High quality GaN layers were grown on Si(111) substrates using high-temperature-grown AlN as buffer layer by rapid thermal process low-pressure metalorganic chemical vapor deposition. The growth and characteristics of AlN buffer layer and the GaN layers were investigated by using scanning electron microscope, X-ray diffraction, photoluminescence (PL), Raman scattering, and Hall measurements at room temperature. It was found that pre-seeding Al to Si surface is a critical condition for AlN growth on Si. Two-dimensional growth of AlN was achieved under optimized conditions. Raman scattering shows a narrow GaN E2 peak and broad AlN E2, E1 peaks. At room temperature, the investigated films are unintentionally doped n-type. The carrier concentration is about 1.3×1017cm−3 and the Hall mobility is about 210cm2/Vs. Metal–semiconductor–metal photoconductive detectors were fabricated on the GaN/Si(111) films. These detectors show a sharp cut-off wavelength at 363nm. A maximum responsivity of 6.9A/W was achieved at 357nm under a 5.0V bias. These results indicate that high quality GaN films on Si(111) can be obtained using the AlN buffer layer, and the potential application of GaN films based on Si substrates.