InN Films (inn + film)

Distribution by Scientific Domains


Selected Abstracts


Optical properties of InN grown on Si(111) substrate

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 5 2010
E. Sakalauskas
Abstract A comprehensive characterization of the optical properties of wurtzite InN films grown by molecular beam epitaxy on Si(111) substrates is presented. Two types of films are investigated in this work: InN on AlN/Si(111) and InN on GaN/AlN/Si(111). Their properties are compared to a layer deposited on GaN/sapphire substrate. The dielectric function (DF) is obtained from spectroscopic ellipsometry (SE). The infrared studies yield the plasma frequency and thus the electron density, while the interband absorption is probed between 0.56 and 9.8,eV. For InN grown on Si(111) substrate, the absorption onset is slightly shifted to higher energies with respect to the InN film grown on GaN/sapphire which can be attributed to higher electron concentrations. Despite this, strongly pronounced optical transitions due to critical points of the band structure are found in the high-energy part of the DF. It emphasizes the already promising quality of the InN films on silicon. Band-gap renormalization (BGR), band filling, and strain are taken into account in order to estimate the intrinsic band gap of wurtzite InN. For the InN layers on silicon, we get a band gap between 0.66 and 0.685,eV. [source]


MOVPE of InN films on GaN templates grown on sapphire and silicon(111) substrates

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2008
Muhammad Jamil
Abstract This paper reports the study of MOVPE of InN on GaN templates grown on sapphire and silicon(111) substrates. Thermodynamic analysis of MOVPE of InN performed using NH3 as nitrogen source and the experimental findings support the droplet-free epitaxial growth of InN under high V/III ratios of input precursors. At a growth pressure of 500 Torr, the optimum growth temperature and V/III ratio of the InN film are 575,650 C and >3 105, respectively. The surface RMS roughness of InN film grown GaN/sapphire template is ,0.3 nm on 2 ,m 2 ,m area, while the RMS roughness of the InN film grown on GaN/Si (111) templates is found as ,0.7 nm. The X-ray diffraction (XRD) measurement reveals the (0002) texture of the InN film on GaN/sapphire template with a FWHM of 281 arcsec of the InN (0002) , rocking curve. For the film grown on GaN/Si template under identical growth conditions, the XRD measurements show the presence of metallic In, in addition to the (0002) orientation of InN layer. ( 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Growth and properties of In-rich InGaN films grown on (0001) sapphire by RF-MBE

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 12 2004
M. Kurouchi
Abstract We have performed detailed investigations of the optical properties of strain-free In-rich InxGa1,xN (0.61 , x , 1.0) films that were grown directly on (0001) sapphire substrates by radio-frequency plasma-excited molecular beam epitaxy. In-composition dependence of photoluminescence peak energy for the InxGa1,xN films, measured at room temperature, exhibited a monotonic and smooth decrease with the increase in the In-composition, approaching to 0.66 eV of a strain-free InN film that was also grown directly on the sapphire substrate. The energy bowing parameter, b was determined to be 1.8 eV using these strain-free InxGa1,xN films. Structural properties of these films are also investigated in detail. ( 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Analysis of the local structure of InN with a bandgap energy of 0.8 and 1.9 eV and annealed InN using X-ray absorption fine structure measurements

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2006
Takao Miyajima
Abstract We compared the local structure around In atoms in microwave-excited MOCVD- and MBE-grown InN film which indicates an absorption edge at 1.9 and 0.8 eV, respectively. The co-ordination numbers of the 1st-nearest neighbor N atoms and the 2nd-nearest neighbor In atoms for MBE-grown InN were n(N) = 3.9 0.5 and n(In) = 12.4 0.9, which are close to the ideal value of n(N) = 4 and n(In) = 12 for InN without defects, respectively. By thermal annealing, the structure of MBE-grown InN was changed from InN to In2O3, and the absorption edge was changed from 0.8 to 3.5 eV. However, the microwave-excited MOCVD-grown InN had no structure of In2O3, and had the reduced co-ordination numbers of the 2nd-nearest neighbor In atoms of n(In) = 10.6-11.7. From these results, we conclude that the origin of the 1.9-eV absorption edge of InN is the imperfections (defects) of the In lattice sites of InN, rather than the generation of In2O3, which has a bandgap energy of 3.5 eV. ( 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Optical anisotropy of A - and M -plane InN grown on free-standing GaN substrates

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 5 2010
P. Schley
Abstract Wurtzite A - and M -plane InN films were grown by molecular beam epitaxy (MBE) on free-standing GaN substrates. Spectroscopic ellipsometry (SE) in the photon energy range from 0.56 up to 15,eV was applied in order to determine the ordinary and extraordinary complex dielectric function (DF) of InN. A distinct optical anisotropy was found over the whole energy range. The extraordinary absorption edge in comparison to the ordinary one is shifted to higher energies confirming previous studies. The investigations in the upper vacuum-ultraviolet (VUV) spectral range (9.5,15,eV) yielded transition energies for four critical points (CPs) of the band structure (BS) which have not been observed so far. [source]


Optical properties of InN grown on Si(111) substrate

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 5 2010
E. Sakalauskas
Abstract A comprehensive characterization of the optical properties of wurtzite InN films grown by molecular beam epitaxy on Si(111) substrates is presented. Two types of films are investigated in this work: InN on AlN/Si(111) and InN on GaN/AlN/Si(111). Their properties are compared to a layer deposited on GaN/sapphire substrate. The dielectric function (DF) is obtained from spectroscopic ellipsometry (SE). The infrared studies yield the plasma frequency and thus the electron density, while the interband absorption is probed between 0.56 and 9.8,eV. For InN grown on Si(111) substrate, the absorption onset is slightly shifted to higher energies with respect to the InN film grown on GaN/sapphire which can be attributed to higher electron concentrations. Despite this, strongly pronounced optical transitions due to critical points of the band structure are found in the high-energy part of the DF. It emphasizes the already promising quality of the InN films on silicon. Band-gap renormalization (BGR), band filling, and strain are taken into account in order to estimate the intrinsic band gap of wurtzite InN. For the InN layers on silicon, we get a band gap between 0.66 and 0.685,eV. [source]


MOVPE of InN films on GaN templates grown on sapphire and silicon(111) substrates

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2008
Muhammad Jamil
Abstract This paper reports the study of MOVPE of InN on GaN templates grown on sapphire and silicon(111) substrates. Thermodynamic analysis of MOVPE of InN performed using NH3 as nitrogen source and the experimental findings support the droplet-free epitaxial growth of InN under high V/III ratios of input precursors. At a growth pressure of 500 Torr, the optimum growth temperature and V/III ratio of the InN film are 575,650 C and >3 105, respectively. The surface RMS roughness of InN film grown GaN/sapphire template is ,0.3 nm on 2 ,m 2 ,m area, while the RMS roughness of the InN film grown on GaN/Si (111) templates is found as ,0.7 nm. The X-ray diffraction (XRD) measurement reveals the (0002) texture of the InN film on GaN/sapphire template with a FWHM of 281 arcsec of the InN (0002) , rocking curve. For the film grown on GaN/Si template under identical growth conditions, the XRD measurements show the presence of metallic In, in addition to the (0002) orientation of InN layer. ( 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Doping-dependence of subband energies in quantized electron accumulation at InN surfaces

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 2 2007
T. D. Veal
Abstract Electron tunnelling spectroscopy is used to investigate the quantized electron accumulation at the surfaces of wurtzite InN with different doping levels. The tunnelling spectra of InN-oxide-tip junctions recorded in air at room temperature exhibit a ,0.6 V plateau, corresponding to the band gap of InN, and a gap between onsets of 1.3 V, consistent with the separation between the valence band maximum and the pinned Fermi level at the oxidized InN surface. Also observed within the tunnelling spectra are additional features between the conduction band minimum and the pinned Fermi level. These features are attributed to surface-bound quantized states associated with the potential well formed by the downward band bending at the InN-oxide interface. Their energetic positions are dependent upon the doping level of the InN films and coincide with calculated subband energies. ( 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


High-quality InN grown on KOH wet etched N-polar InN template by RF-MBE

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2006
D. Muto
Abstract We have succeeded in dramatically decreasing the density of dislocations in InN by regrowing InN films on micro-facetted N-polar InN templates. The micro-facetted N-polar InN templates were formed by wet etching in a 10 mol/l KOH solution. InN films were regrown on the micro-facetted N-polar InN templates and on flat surface N-polar InN templates for comparison by radio-frequency plasma-assisted molecular beam epitaxy. InN regrown on micro-facetted InN had considerably smaller twist distribution than that grown on the flat InN templates. From transmission electron microscopy observation, it was confirmed that the InN grown on the micro-facetted InN template had much lower density of dislocations than that grown on the flat InN template, and moreover the propagation of edge dislocations was almost completely terminated at the interface between the regrown InN and the micro-facetted InN template. Based on the results, we propose that regrowth of InN on micro-facetted InN templates is an effective way to obtain high-quality InN films. ( 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Stoichiometry effects and the Moss,Burstein effect for InN

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2006
K. S. A. Butcher
Abstract We examine the Moss,Burstein effect for InN and demonstrate an independent method for determing its magnitude for high carrier concentration material. Consequently it is shown that the extent of the Moss,Burstein effect is less than 0.72 eV for a high carrier concentration sample with a 1.88 eV absorption edge. Early results are also provided for high band-gap low carrier concentration InN films that can be grown reprodcibly, vindicating the work of early groups in the field. The role of stoichiometry is examined in relation to point defects that appear to be common to many forms of InN. ( 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Raman and transmission electron microscopy characterization of InN samples grown on GaN/Al2O3 by molecular beam epitaxy

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 7 2006
J. Arvanitidis
Abstract Raman spectroscopy and transmission electron microscopy were employed to study the vibrational properties and the microstructure of epitaxially grown InN films on GaN/Al2O3 templates. The variations of the InN lattice constants, as deduced by electron diffraction analysis, along with the red-shifted E22 mode frequency reveal that InN films exhibit residual tensile stress, strongly dependent on the epilayer growth temperature. Threading dislocations are the dominant structural defects in the films, having a density in the order of 109,1010 cm,2. Profile analysis of the E22 Raman peak by means of the Spatial Correlation Model provides useful information concerning the effective mean length for free phonon propagation (L), which is a measure of the structural quality of the samples. In all the studied samples, L monotonically increases with decreasing threading dislocation density of pure screw and mixed type character. ( 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Effective mass of InN estimated by Raman scattering

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7-8 2010
Jung Gon Kim
Abstract We have estimated the longitudinal effective mass (m,) of electron in n-type InN films by Raman scattering. The samples were grown by MOVPE (metal organic vapor phase epitaxy) with free carrier concentration of n =6.71018 -9.91018 cm -3 according to Hall measurement. A weak Raman signal observed at ,430 cm -1 at room temperature was sharpened and shifted to higher frequency toward the A1(TO)-phonon mode at 447 cm -1 with increasing n. This mode was assigned to the lower branch (L - ) of the longitudinal-optic-phonon-plasmon-coupled (LOPC) mode. The line shape was carefully analyzed by a semi-classical line-shape fitting analysis assuming deformation potential and electro-optic coupling mechanisms for the light scattering process. A line-shape fitting analysis was conducted by adjusting three major parameters; electron density, effective mass and plasmon damping rate. The analysis well reproduced values of electron density and mobility deduced by Hall measurement. Electron effective mass of m,*/m0 = 0.05 (0.01) was also obtained as the best-fit parameter. The result agrees well with previous data obtained by other optical methods. ( 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


RF-MBE growth of InN on 4H-SiC (0001) with off-angles

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7-8 2010
Misao Orihara
Abstract We have grown InN on 4H-SiC (0001) substrates with various off-angles by RF-N2 plasma molecular beam epitaxy (RF-MBE). Scanning electron microscope observation revealed that InN films grown on 4H-SiC (0001) substrates with off-angles of 4 and 8 are very smooth and that there are no voids which have often observed for InN epitaxial layers. X-ray diffraction reciprocal space maps for InN grown on 4H-SiC (0001) showed that the c-axes of InN grown on 4H-SiC 4 and 8 off substrates are inclined by 0.35 and 0.8, respectively, toward the misorientation of the substrate while the c-axis of InN is parallel to that of 4H-SiC for the on-axis substrate. Strong PL peak was observed from InN grown on 4 off substrate at 0.68 eV at 15 K. The PL peak was clearly observed even at room temperature and simply shifted to lower energies with increasing temperature. The difference in the PL peak energy between at 15 K and 300 K was 20 meV, which is reasonable taking into account the difference in the thermal coefficients of InN and SiC ( 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Photoluminescence of cubic InN films on MgO (001) substrates

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2008
T. Inoue
Abstract We have studied photoluminescence from cubic InN films grown on MgO substrates with a cubic GaN underlayer by RF N2 plasma molecular beam epitaxy. A single PL peak was observed at 0.47 eV. By analyzing the reflectance spectra of cubic InN films, we could derive the refractive index and extinction coefficient, and found the band gap energy of cubic InN is 0.48 eV, indicating that the PL peak observed at 0.47 eV is due to the interband transition of cubic InN. The difference in the PL peak energy between hexagonal and cubic InN is in good agreement with that predicted by ab-initio calculations. ( 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


NH3/TMI molar ratio dependence of electrical and optical properties for atmospheric-pressure MOVPE InN

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2006
A. Yamamoto
Abstract The electrical and optical properties for atmospheric-pressure MOVPE InN have been studied as a function of NH3/TMI molar ratio during the growth. Residual carrier (electron) concentration is decreased with increasing NH3/TMI molar ratio. PL peak energy is also shifted to a low energy side with increasing NH3/TMI molar ratio. Hall mobility of InN is almost independent on NH3/TMI molar ratio and is rather decreased at a high NH3/TMI molar ratio. The highest mobility is obtained for a sample grown at a relatively low NH3/TMI molar ratio. The grain size of the InN films is decreased with increasing NH3/TMI molar ratio. The lowest carrier concentration of 4.51018 cm,3 and highest mobility of 1100 cm2/Vs obtained here are the best data for MOVPE InN ever reported. Based on these results, the most probable candidate for donors and the dominant carrier-scattering mechanism for atmospheric-pressure MOVPE InN are discussed. ( 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Growth of InN on 6H-SiC by plasma assisted molecular beam epitaxy

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2006
April S. Brown
Abstract We have investigated the growth of InN films by plasma assisted molecular beam epitaxy on the Si-face of 6H-SiC(0001). Growth is performed under In-rich conditions using a two-step process consisting of the deposition of a thin, low-temperature 350 C InN buffer layer, followed by the subsequent deposition of the InN epitaxial layer at 450 C. The effect of buffer annealing is investigated. The structural and optical evolution of the growing layer has been monitored in real time using RHEED and spectroscopic ellipsometry. Structural, morphological, electrical and optic properties are discussed. ( 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]