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Abstract: In this paper, we report the studies on the hetero-epitaxial growth of wurtzite indium nitride (InN) thin films on oxide buffer layer by RF metal-organic molecular beam epitaxy (RF-MOMBE) system. Oxide buffer layer was pre-sputtered using RF sputtering technique. The structural properties and surface morphology were investigated by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). We also investigated the optical properties by temperature-dependence photoluminescence (PL). Near-infrared emission peak centered at 0.75eV was observed from PL measurement. The irregular and asymmetric PL line shape was caused by absorbed moisture and surface electron accumulation in InN films. According to the fitting results of PL spectra measured at 20K, we could estimate the bandgap and Fermi level is 0.65eV and 113meV, which confirm to previous reports. Our results reveal that the oxide thin film could be a suitable buffer layer for engineering the growth of InN on sapphire wafer, and it might be also applicable for other lattice-mismatched III-V hetero-epitaxial systems. [Copyright &y& Elsevier]

Abstract: In this paper, high-quality wurtzite indium nitride was epi-grown on sapphire substrates by plasma-assisted metal-organic molecule beam epitaxy system (PA-MOMBE). Structural and electrical properties of the InN films were significantly improved by employing a GaN buffer layer. In addition, high-resolution X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy (TEM), Hall Effect, Raman and photoluminescence spectroscopy were carried out to characterize the effect of the growth temperature on structural and optoelectronic properties. It was found that highly c-axis oriented InN epilayer can be obtained by optimizing growth conditions. TEM images reveal that the epitaxially grown InN/GaN interface is sharp, and the spacing of the InN(0002) lattice plane is about 0.57nm. Raman spectra also show a sharp peak at 491cm−1 attributed to the E2(high) mode of wurtzite InN. These results indicate that the improvement of InN material quality can be achieved using heteroepitaxy on GaN/sapphire templates. [Copyright &y& Elsevier]

Abstract: We have investigated the effects of III/V ratio on the properties of InN films grown on sapphire substrates with oxide buffer by metalorganic molecular-beam epitaxy. The structural, optical and electrical properties of the InN films were investigated by X-ray diffraction, scanning electron microscopy, Hall-effect and temperature-dependent photoluminescence (PL) measurements. Near-infrared emission peaks between 0.74 and 0.78eV were observed. On increasing the III/V flux ratio, the PL emission peak red-shifted that is related to the reduction in carrier concentration. In addition, the PL spectra show an abnormal behavior with increase in temperature. The temperature-dependence PL spectra exhibit blue-shift as the temperature increased up to 150K and then red-shift, reflecting a competition between the blue-shift induced by thermal screening and the red-shift induced by electron–phonon interaction. [Copyright &y& Elsevier]