Effect of Al pre-deposition on AlN buffer layer and GaN film grown on Si (111) substrate by MOCVD (original) (raw)
Related papers
The effect of AlN buffer layer on GaN grown on (111)-oriented Si substrates by MOCVD
Journal of Crystal Growth, 2000
GaN "lms were grown by metal organic chemical vapor deposition on (1 1 1)Si substrates, using AlN as a bu!er layer. The in#uence of the AlN bu!er layer growth temperature and growth duration on the morphology and preferred orientation of GaN "lms was studied. Drastic enhancement of epitaxial registration was observed with increasing bu!er growth temperature. A sharp transition in the growth mode occurred at 7603C. For that temperature, an optimal bu!er layer growth duration was found. The use of March parameter as a "gure of merit in X-ray di!raction testing of textured GaN "lms is proposed.
Characterization of an AlN buffer layer and a thick-GaN layer grown on sapphire substrate by MOCVD
Journal of Materials Science, 2010
An AlN buffer layer and a thick-GaN layer for high-electron-mobility transistors (HEMTs) were grown on sapphire substrate by metal-organic chemical vapor deposition (MOCVD). The structural and morphological properties of the layers were investigated by high resolution X-ray diffraction (HRXRD) and atomic force microscopy (AFM) techniques. The optical quality of the thick-GaN layer was also evaluated in detail by a photoluminescence (PL) measurement. It was found that the AlN buffer layer possesses high crystal quality and an atomically flat surface with a root-mean-square (rms) roughness of 0.16 nm. The screw-and edge-type dislocation densities of the thick-GaN layer were determined as 5.4 9 10 7 and 5.0 9 10 9 cm-2 by means of the mosaic crystal model, respectively. It was observed that the GaN layer has a smooth surface with an rms of 0.84 nm. Furthermore, the dark spot density of the GaN surface was estimated as 6.5 9 10 8 cm-2 over a scan area of 4 lm 2 .
Applied Physics Letters, 2007
High quality GaN film was successfully grown on 150 mm Si ͑111͒ substrate by metal-organic vapor phase epitaxy method using AlN multilayer combined with graded AlGaN layer as buffer. The buffer layer structure, film quality, and film thickness are critical for the growth of the crack-free GaN film on Si ͑111͒ substrate. Using multilayer AlN films grown at different temperatures combined with graded Al 1−x Ga x N film as the buffer, the tensile stress on the buffer layer was reduced and the compressive stress on the GaN film was increased. As a result, high quality 0.5 m crack-free GaN epitaxial layer was successfully grown on 6 in. Si substrate.
Investigation of GaN layer grown on Si(1 1 1) substrate using an ultrathin AlN wetting layer
Journal of Crystal Growth, 2002
High-quality GaN epilayers were grown on Si(1 1 1) substrate by metalorganic chemical vapor deposition. The growth process was featured by using an ultrathin AlN wetting layer (WL) in combination with a low-temperature (LT) GaN nucleation layer (NL). The full-width at half-maximum (FWHM) of the X-ray rocking curve for the GaN (0 0 0 2) diffraction was 15 arcmin. The dislocation density estimated from TEM investigation was found to be of the order of 10 9 cm À2 . The FWHM of the dominant band edge emission peak of the GaN was measured to be 47 meV by photoluminescence measurement at room temperature. The ultrathin AlN WL was produced by nitridation of the aluminium pre-covered substrate surface. The reflection high-energy electron diffraction showed that the AlN WL was wurtzite and the surface morphology was like the nitridated surface of sapphire by the atomic force microscopy measurement. X-ray photoelectron spectroscopy measurement showed that Si and Si x N y at a certain concentration were intermixed in the AlN WL. This study suggests that by employing an appropriate WL combined with a LT NL, high-quality heteroepitaxy is achievable even with large mismatch. r
Current Applied Physics, 2009
In the present paper, the effects of nitridation on the quality of GaN epitaxial films grown on Si(1 1 1) substrates by metal-organic chemical vapor phase deposition (MOCVD) are discussed. A series of GaN layers were grown on Si(1 1 1) under various conditions and characterized by Nomarski microscopy (NM), atomic force microscopy (AFM), high resolution X-ray diffraction (HRXRD), and room temperature (RT) photoluminescence (PL) measurements. Firstly, we optimized LT-AlN/HT-AlN/Si(1 1 1) templates and graded AlGaN intermediate layers thicknesses. In order to prevent stress relaxation, step-graded AlGaN layers were introduced along with a crack-free GaN layer of thickness exceeding 2.2 lm. Secondly, the effect of in situ substrate nitridation and the insertion of an Si x N y intermediate layer on the GaN crystalline quality was investigated. Our measurements show that the nitridation position greatly influences the surface morphology and PL and XRD spectra of GaN grown atop the Si x N y layer. The X-ray diffraction and PL measurements results confirmed that the single-crystalline wurtzite GaN was successfully grown in samples A (without Si x N y layer) and B (with Si x N y layer on ). The resulting GaN film surfaces were flat, mirror-like, and crack-free. The full-width-at-half maximum (FWHM) of the X-ray rocking curve for (0 0 0 2) diffraction from the GaN epilayer of the sample B in x-scan was 492 arcsec. The PL spectrum at room temperature showed that the GaN epilayer had a light emission at a wavelength of 365 nm with a FWHM of 6.6 nm (33.2 meV). In sample B, the insertion of a Si x N y intermediate layer significantly improved the optical and structural properties. In sample C (with Si x N y layer on Al 0.11 Ga 0.89 N interlayer). The in situ depositing of the, however, we did not obtain any improvements in the optical or structural properties.
Journal of Vacuum Science & Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena, 2010
GaN film grown on Si substrate using multilayer AlN/AlxGa1−xN buffer is studied by the low-pressure metal-organic chemical-vapor deposition method. The AlxGa1−xN films with Al composition varying from 1 to 0.66 were used to accommodate the stress induced between GaN and the Si substrate during GaN growth. The correlation of the Al composition in the AlxGa1−xN films with respect to the stress induced in the GaN film grown was studied using high-resolution x-ray diffraction, including symmetrical and asymmetrical ω/2θ scans and reciprocal space maps. It is found that with proper design of the Al composition in the AlxGa1−xN buffer layer, crack-free GaN film can be successfully grown on 6 in. Si (111) substrates using multilayer AlN and AlxGa1−xN buffer layers.
High Quality GaN Layers Grown by Metalorganic Chemical Vapor Deposition on Si(111) Substrates
physica status solidi (a), 1999
GaN layers are grown onto silicon (111) substrates by metalorganic chemical vapor phase deposition (MOCVD). The X-ray and photoluminescence spectra as well as the surface morphologies of the layers are comparable to the characteristics of GaN layers grown on sapphire substrates. Linewidths of 610 arcsec in the case of the GaN(0002) reflection in the X-ray w-scan and 13 meV at 10 K for the dominant excitonic photoluminescence at 3.44 eV as well as a surface roughness below 2 nm (rms) are observed. The high quality has been achieved by a careful optimization of AlAs/AlN buffer layers on the Si substrates.
Influence of high-temperature AIN buffer thickness on the properties of GaN grown on Si(1 1 1)
Journal of Crystal Growth, 2003
The influences of AlN buffer thickness on the optical and the crystalline properties of metalorganic chemical vapor deposition wurtzite GaN layers on Si(1 1 1) substrate have been investigated. High-resolution X-ray diffraction and photoluminescence measurement reveal that the thickness of AlN buffer exerts a strong influence on the distribution of dislocation and stress in GaN epilayer. The evidence is further reinforced by atomic force microscopic observation of AlN nucleation process. The optimum thickness of AlN buffer to effectively suppress Si diffusion has been determined by secondary-ion mass spectroscopy to be in the range of 13-20 nm. In addition, it is found that appropriate Si diffusion in AlN buffer helps to compensate the tensile strain in GaN, which subsequently improves the optical quality of GaN on Si(1 1 1), and reduces the cracks over the GaN surface.