InN Layers (inn + layer)

Distribution by Scientific Domains


Selected Abstracts


Investigation of polarity dependent InN{0001} decomposition in N2 and H2 ambient

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue S2 2009
R. Togashi
Abstract The polarity dependence of decomposition of the (0001) In- and (000) N-polarity InN layers grown by hydride vapor phase epitaxy (HVPE) on freestanding GaN substrates was investigated. In flowing N2, In- and N-polarity InN layers start to decompose over 550 and 610 C, respectively. Therefore, the N-polarity InN layer is more stable than the In-polarity InN layer. On the other hand, in flowing H2, InN layers of both polarities start to react with H2 at a low temperature of 350 C leaving In droplets on the surfaces. Further more, the decomposition rate of the N-polarity InN layer is larger than that of the In-polarity InN layer below approximately 450 C, while the decomposition rate of the In-polarity InN layer is larger than that of the N-polarity InN above 450 C. An Arrhenius plot of the decomposition rates revealed that the activation energies, EA, for the decomposition reactions of In- and N- polarity InN layers are 168 and 107 kJ/mol, respectively, which are much smaller than that for GaN and AlN decomposition. ( 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Formation of "air-gap" structure at a GaN epilayer/substrate interface by using an InN interlayer

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2003
A. Yamamoto
Abstract We propose a new technique for "air-gap" formation at a GaN/sapphire interface by using an InN interlayer. This is aimed to grow epitaxial GaN films with reduced stress and cracks. First, an InN interlayer of about 0.2 ,m thick is grown at 600 C in atmospheric pressure. Then a 30 nm-thick GaN buffer layer is grown on the InN layer at 550 C. The substrate temperature is ramped up to 1000 C in the NH3 flow, and finally a 1.5 ,m-thick GaN epilayer is grown on the annealed GaN buffer layer using nitrogen carrier gas. Consequently, an "air-gap" structure is naturally formed close to the substrate surface. During the ramping period of substrate temperature, the InN layer decomposes due to its thermal instability and metallic In is formed. It is found that metallic In drops as a result of InN decomposition contribute to the air-gap formation. No cracks are found on the GaN surface and a reduced stress in the layer is confirmed by PL and Raman shift measurements. ( 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


The growth of In-rich InGaN/GaN single quantum wells by metalorganic chemical vapor deposition

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2003
Hyun Jin Kim
Abstract In-rich InGaN/GaN single quantum wells were grown by metalorganic chemical vapor deposition for the first time to the best of our knowledge. The structures consist of a 2-,m thick GaN buffer layer, a 2-nm thick In-rich InGaN single quantum well, and a 20 nm thick GaN capping layer. Single quantum well structures were examined by transmission electron microscopy. Photoluminescence emissions from the single quantum well samples were observed at wavelengths ranged from 400 nm to 500 nm depending upon the growth conditions of the InN layer. From a simple energy level calculation, we found the possibility of extremely large emission peak shift with well thickness. [source]


Development of InN metalorganic vapor phase epitaxy using in-situ spectroscopic ellipsometry

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 10-11 2005
M. Drago
Abstract Metalorganic vapor phase epitaxy of InN layers on sapphire was studied in-situ by spectroscopic ellipsometry (SE), ex-situ atomic force microscopy and optical microscopy. Surface morphology has been largely improved by using nitrogen instead of hydrogen as carrier gas during sapphire nitridation. Using the sensitivity of in-situ SE with respect to roughness we established a new growth procedure with low V/III ratio (104) at high temperature (580 C) and growth rates as high as 350 nm/h, leading to improved electronic layer properties and allowing for growth of comparably thick layers. ( 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Optical properties of InN grown on templates with controlled surface polarities

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 10 2010
Ronny Kirste
Abstract The structural and optical properties of InN layers grown on GaN/sapphire templates with controlled Ga-/N-polar surfaces are investigated. Raman spectroscopy and XRD reciprocal space map analysis suggest that the InN layers were grown strain free with a high crystal quality. A line shape analysis of the A1(LO) Raman mode yields to a decreasing carrier concentration for the sample grown on Ga-polar substrate. Low temperature photoluminescence measurements exhibit a shift to lower energies of the luminescence maximum for the sample grown on Ga-polar GaN probably due to a reduced carrier concentration and thus, a decreased Burstein,Moss shift. Following this, we demonstrate that the use of polarity controlled GaN/sapphire substrates leads to unstrained layers with good structural and optical properties. [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]


Recombination processes with and without momentum conservation in degenerate InN

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2006
E. Valcheva
Abstract We report on a theoretical approach in which the two cases of recombination with and without momentum conservation in optically excited high carrier concentration InN are considered. The calculations are used to analyze emission spectra of n-type InN layers of electron concentrations from 7.7 1017 to 1.4 1019 cm,3 studied in the temperature range between 9 and 100 K. The spectra peak near 0.7 eV and the applicability of the two approaches with increasing carrier concentration is estimated. Different transition mechanisms are considered in order to properly account for the observed features in the spectra. Recombination processes involving acceptor- and donor-like localized states are discussed. ( 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Investigation of InN layers grown by MOCVD using analytical and high resolution TEM: The structure, band gap, role of the buffer layers

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2006
P. Ruterana
Abstract In this work we investigate the microstructure of InN layers grown by MOCVD on different buffer layers using TEM (InN, GaN). The large mismatch between the various lattices (InN, sapphire or GaN) leads to particular interface structures. Our local analysis allows to show that at atomic scale, the material has the InN lattice parameters and that no metallic In precipitates are present, meaning that the PL emission below 0.8 eV is a genuine property of the InN semiconductor. It is also shown that the N polar layers, which exhibit a 2D growth, have poorer PL emission than In polar layers. ( 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


The microstructure and properties of InN layers

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 5 2010
P. Ruterana
Abstract A series of InN layers grown by different techniques has been investigated by transmission electron microscopy, photoluminescence and Raman spectroscopy. The polarity is shown to be determined by the underlying GaN template. In these In polar layers, the c -screw dislocations density is low and that of a -type dislocations is in the high-109 cm -2 range. The dislocation density tends to decrease towards the surface. Along the first 0.5 ,m, and particularly in the samples grown by hydride vapour epitaxy, we observe a large number of stacking faults, which probably contribute to the dislocation density reduction. The optical band gap in MBE and MOVPE samples is between 0.6 and 0.7 eV, but that of the HVPE templates is above 1 eV. Estimations from Raman data show that this behaviour correlates well with the residual carrier concentration. ( 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Investigation of polarity dependent InN{0001} decomposition in N2 and H2 ambient

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue S2 2009
R. Togashi
Abstract The polarity dependence of decomposition of the (0001) In- and (000) N-polarity InN layers grown by hydride vapor phase epitaxy (HVPE) on freestanding GaN substrates was investigated. In flowing N2, In- and N-polarity InN layers start to decompose over 550 and 610 C, respectively. Therefore, the N-polarity InN layer is more stable than the In-polarity InN layer. On the other hand, in flowing H2, InN layers of both polarities start to react with H2 at a low temperature of 350 C leaving In droplets on the surfaces. Further more, the decomposition rate of the N-polarity InN layer is larger than that of the In-polarity InN layer below approximately 450 C, while the decomposition rate of the In-polarity InN layer is larger than that of the N-polarity InN above 450 C. An Arrhenius plot of the decomposition rates revealed that the activation energies, EA, for the decomposition reactions of In- and N- polarity InN layers are 168 and 107 kJ/mol, respectively, which are much smaller than that for GaN and AlN decomposition. ( 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Metastable cubic InN layers on GaAs (001) substrates grown by MBE: Growth condition and crystal structure

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue S2 2009
Sakuntam Sanorpim
Abstract Transmission electron microscopy and high resolution X-ray diffraction were applied to characterize the crystal structure and its modification in c-InN layers on GaAs (001) substrates grown by rf-plasma assisted molecular beam epitaxy. The layer quality was shown to depend on growth conditions, namely In- and N-rich conditions. The best quality of c-InN layers was achieved by "stoichiometric" growth under the In-rich condition, resulting in In-rich layers with a small amount of hexagonal-phase inclusion (,8%). On the other hand, nucleation and growth of N-rich layers are shown to result in a high density of stacking faults which drastically decreases toward the InN surface. It is argued that the presence of stacking faults contributes to the structural modification in these layers. We found that the existence of a structural modification from cubic to mixed cubic/hexagonal phase in microstructure of the N-rich layers exhibit higher hexagonal-phase incorporation than that of the In-rich layers. ( 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Electrical properties and optical absorption in InN:In structures

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2008
T. A. Komissarova
Abstract Electrophysical and optical absorption measurements have been performed for conventional InN epilayers and InN:In composite structures grown by plasma-assisted molecular beam epitaxy. It is shown that intentional periodical introduction of In metallic inclusions into InN layers results in formation of inhomogeneous arrays of clusters. Their presence modifies the shape of absorption spectra. At the same time, significant amount of indium (up to 1/3 of a thickness) in these structures does not influence noticeably the carrier concentration and mobility. These parameters fall in the range of published data for the conventional InN layers. These finding can indicate that formation of In clusters in InN is a more frequent event than it is currently accepted. ( 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Origins of n-type residual carriers in RF-MOMBE grown InN layers

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2007
Kosuke Iwao
Abstract We have investigated quantitatively on the origins of residual electrons in InN layers to make clear some roles of oxygen incorporation for band-gap widening. It has been found out that a linear relation was observed between oxygen and residual electron concentrations for InN layers grown by RF-MOMBE using TMIn source, although the residual electron concentration is super-linearly dependent on oxygen concentration for InN layers grown by RF-MBE using metal In source. The experimental results strongly indicate that oxygen atoms and/or nitrogen vacancies induced by oxygen incorporation are major origins of the residual carrier concentrations. ( 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]