共查询到20条相似文献,搜索用时 15 毫秒
1.
A. Gouyé O. Kermarrec A. Halimaoui Y. Campidelli D. Rouchon M. Burdin P. Holliger D. Bensahel 《Journal of Crystal Growth》2009,311(13):3522-3527
Si homo-epitaxial growth by low-temperature reduced pressure chemical vapor deposition (RPCVD) using trisilane (Si3H8) has been investigated. The CVD growth of Si films from trisilane and silane on Si substrates are compared at temperatures between 500 and 950 °C. It is demonstrated that trisilane efficiency increases versus silane's one as the surface temperature decreases. Si epilayers from trisilane, with low surface roughness, are achieved at 600 and 550 °C with a growth rate equal to 12.4 and 4.3 nm min−1, respectively. It is also shown that Si1−xGex layers can be deposited using trisilane chemistry. 相似文献
2.
Jie-Jun Wu Yusuke KatagiriKazuki Okuura Da-Bing LiHideto Miyake Kazumasa Hiramatsu 《Journal of Crystal Growth》2009,311(14):3801-3805
A 4–6 μm thick a-plane (1 1 2¯ 0) AlN was grown on r-plane sapphire substrate by low-pressure hydride vapor phase epitaxy (LP-HVPE), using a direct growth without any nitridation and buffer layer, a single-step nitridation growth, a two-step nitridation growth and a two-step buffer growth method. For the two-step buffer growth procedure, smoother surface is observed with the lower full widths at half maximum (FWHM) of X-ray rocking curves (XRC) compared with the other two kinds of nitridation procedures. A smaller FWHM of in-plane XRC peak anisotropy features are reversed, which is consistent with the smaller in-plane stress anisotropic distribution in a-plane AlN, when the two-step nitridation or buffer growth method is used. In four kinds of initial growth procedures, the two-step buffer method is the suitable method for the growth of a-plane AlN by HVPE with the high crystal quality and more isotropic distribution. 相似文献
3.
Jie-Jun Wu Kazukeru OkuuraKohei Fujita Kenta OkumuraHideto Miyake Kazumasa Hiramatsu 《Journal of Crystal Growth》2009,311(20):4473-4477
The effect of the off-cut angle of an r-plane sapphire substrate has been investigated on the growth of a-plane AlN thick layer by low-pressure hydride vapor phase epitaxy (LP-HVPE). The off-cut angle (θ) was changed from +5.0° (close to c-axis) to −5.0° (close to m-axis). Results show that the crystalline quality and surface morphology are very sensitive to the sign of θ off-angle. The plus θ off-angle is found to be dramatically reduce the full-widths at half-maximum (FWHM) of X-ray rocking curves (XRC), compared with the minus θ off-angle. In-plane FWHM anisotropic feature marked as M- or W-shape dependence on azimuth angle was observed for a-plane AlN. The shape and degree of anisotropy depend on the sign of θ off-angle, while the plus of θ off-angle will leads to the W-shape and the decreased anisotropy. The minimum crystal tilts and twists of the films are observed for the vicinal sapphires with the plus off-angles of +0.2° to +1.0°. 相似文献
4.
Neyda Baguer Violeta Georgieva Lazaro Calderin Ilian T. Todorov Sake Van Gils Annemie Bogaerts 《Journal of Crystal Growth》2009,311(16):4034-4043
The nucleation and growth of titanium dioxide (TiO2) and zinc oxide (ZnO) thin films on Fe2O3 (hematite), Al2O3 (α-alumina) and SiO2 (α-quartz) are studied by molecular dynamics simulations. The results show the formation of a strong interface region between the substrate and the film in the six systems studied here. A combination of polycrystalline and amorphous phases are observed in the TiO2 films grown on the three substrates. ZnO deposition on the Fe2O3 and Al2O3 crystals yields a monocrystalline film growth. The ZnO film deposited on the SiO2 crystal exhibits less crystallinity. The simulation results are compared with experimental results available in the literature. 相似文献
5.
J.R. Grandusky J.A. Smart M.C. Mendrick L.J. Schowalter K.X. Chen E.F. Schubert 《Journal of Crystal Growth》2009,311(10):2864-2866
Recently it has been discovered that when growing AlxGa1−xN on low-defect-density bulk AlN substrates pseudomorphic layers can be achieved with a thickness far exceeding the critical thickness as given by the Matthews and Blakeslee model. For instance, the critical thickness of an AlxGa1−xN layer (with x=0.6) is about 40 nm thick. However we have been able to grow layers with this composition that are pseudomorphic with a thickness exceeding the critical thickness by more than an order of magnitude. This work defines the limits of pseudomorphic growth on low defect density, bulk AlN substrates to obtain low defect density, high-power UV LEDs. 相似文献
6.
Qian Sun Christopher D. Yerino Yu Zhang Yong Suk Cho Soon-Yong Kwon Bo Hyun Kong Hyung Koun Cho In-Hwan Lee Jung Han 《Journal of Crystal Growth》2009,311(15):3824-3829
This paper reports a study of the effect of NH3 flow rate on m-plane GaN growth on m-plane SiC with an AlN buffer layer. It is found that a reduced NH3 flow rate during m-plane GaN growth can greatly improve the recovery of in situ optical reflectance and the surface morphology, and narrow down the on-axis (1 0 1¯ 0) X-ray rocking curve (XRC) measured along the in-plane a-axis. The surface striation along the in-plane a-axis, a result of GaN island coalescence along the in-plane c-axis, strongly depends on the NH3 flow rate, an observation consistent with our recent study of kinetic Wulff plots. The pronounced broadening of the (1 0 1¯ 0) XRC measured along the c-axis is attributed to the limited lateral coherence length of GaN domains along the c-axis, due to the presence of a high density of basal-plane stacking faults, most of which are formed at the GaN/AlN interface, according to transmission electron microscopy. 相似文献
7.
Jaewan Chang Yoon-Seok ParkJong-Woo Lee Sang-Koog Kim 《Journal of Crystal Growth》2009,311(14):3771-3774
We report on growth-mode transitions in the growth of SrRuO3 thin films on atomically flat Ti4+ single-terminated SrTiO3 (1 1 1) substrates, investigated by reflection high-energy electron diffraction and atomic force microscopy. Over the first ~9 unit cells, the dominant growth mode changes from island to layer-by-layer for the growth rate of 0.074 unit cells/s and the growth temperature of 700 °C. Moreover, in the course of growing SrRuO3 films, the governing growth mode of interest can be manipulated by changing the growth temperature and the growth rate, which change allows for the selection of the desired layer-by-layer mode. The present study thus paves the way for integrations of SrRuO3 thin layers into (1 1 1)-orientated oxide heterostructures, and hence multi-functional devices, requiring control of the sharp atomic-level interfaces and the layer-by-layer growth mode. 相似文献
8.
Phannee Saengkaew Armin DadgarJuergen Blaesing Thomas HempelPeter Veit Juergen ChristenAlois Krost 《Journal of Crystal Growth》2009,311(14):3742-3748
We present MOVPE-grown, high-quality AlxGa1−x N layers with Al content up to x=0.65 on Si (1 1 1) substrates. Crack-free layers with smooth surface and low defect density are obtained with optimized AlN-based seeding and buffer layers. High-temperature AlN seeding layers and (low temperature (LT)/high temperature (HT)) AlN-based superlattices (SLs) as buffer layers are efficient in reducing the dislocation density and in-plane residual strain. The crystalline quality of AlxGa1−xN was characterized by high-resolution X-ray diffraction (XRD). With optimized AlN-based seeding and SL buffer layers, best ω-FWHMs of the (0 0 0 2) reflection of 540 and 1400 arcsec for the (1 0 1¯ 0) reflection were achieved for a ∼1-μm-thick Al0.1Ga0.9N layer and 1010 and 1560 arcsec for the (0 0 0 2) and (1 0 1¯ 0) reflection of a ∼500-nm-thick Al0.65Ga0.35N layer. AFM and FE-SEM measurements were used to study the surface morphology and TEM cross-section measurements to determine the dislocation behaviour. With a high crystalline quality and good optical properties, AlxGa1−x N layers can be applied to grow electronic and optoelectronic device structures on silicon substrates in further investigations. 相似文献
9.
We investigated the effect of growth parameters for obtaining high-quality AlN grown directly on sapphire substrates by a hybridized method, derived from simultaneous source supply and conventional migration-enhanced epitaxy. At an optimal growth temperature of 1200 °C, AlN was atomically smooth and pit-free, while below and above 1200 °C, AlN was rough and with pits, respectively. Surface morphologies also depended on the V/III ratio. Rough surfaces became atomically smooth but then pits appeared, as the V/III ratio increased. The crystallinity revealed by X-ray diffraction changed accordingly. The 600-nm-thick AlN grown under the optimal conditions showed X-ray line widths of as narrow as ∼43 and ∼250 arcsec for (0 0 0 2) and (1 0 1¯ 2) diffractions, respectively. 相似文献
10.
Hydrogenated carbon nitride (a-CN:H) films were deposited on n-type (1 0 0) silicon substrates making use of direct current radio frequency plasma enhanced chemical vapor deposition (DC-RF-PECVD), using a gas mixture of CH4 and N2 as the source gas in range of N2/CH4 flow ratio from 1/3 to 3/1 (sccm). The deposition rate, composition and bonding structure of the a-CN:H films were characterized by means of X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectrometry (FTIR). The mechanical properties of the deposited films were evaluated using nano-indentation test. It was found that the parameter for the DC-RF-PECVD process had significant effects on the growth rate, structure and properties of the deposited films. The deposition rate of the films decreased clearly, while the N/C ratio in the films increased with increasing N2/CH4 flow ratio. CN radicals were remarkably formed in the deposited films at different N2/CH4 flow ratio, and their contents are related to the nitrogen concentrations in the deposited films. Moreover, the hardness and Young’s modulus of the a-CN:H films sharply increased at first with increasing N2/CH4 flow ratio, then dramatically decreased with further increase of the N2/CH4 flow ratio, and the a-CN:H film deposited at 1/1 had the maximum hardness and Young’s modulus. In addition, the structural transformation from sp3-like to sp2-like carbon-nitrogen network in the deposited films also was revealed. 相似文献
11.
In the present work we have grown twin-free single crystal metal films of iridium (Ir), rhodium (Rh), platinum (Pt) and ruthenium (Ru) on silicon (1 1 1) substrates via an yttria-stabilized zirconia (YSZ) buffer layer. A prerequisite for the realisation of heteroepitaxial metal films without additional texture components was the twin-free deposition of the YSZ films by pulsed laser deposition (PLD). For the metal films on top, a novel two-step growth process was applied with an extremely low deposition rate for the first 20 nm. For all metals, a drastic texture improvement by up to a factor of 9 could be observed compared to the oxide buffer layer. Minimum values were 0.18° (Ir) and 0.12° (Rh) for tilt and twist, respectively. For all four metals investigated, twin-free epitaxial films could be grown on YSZ/Si(1 1 1) whereas the twinning problem for platinum films was solved by decoupling the Pt-YSZ interface via an additional iridium interlayer. The grown metal/YSZ/Si(1 1 1) multilayer samples offer the possibility to integrate a variety of interesting nanostructures and functional materials on silicon. They are now available in 4 in wafer size. 相似文献
12.
Mitsuhisa Narukawa Shinya KoideHideto Miyake Kazumasa Hiramatsu 《Journal of Crystal Growth》2009,311(10):2970-2972
Undoped and Zn-doped GaN nanowires were synthesized by chemical vapor deposition (CVD), and the effects of substrates, catalysts and precursors were studied. A high density of GaN nanowires was obtained. The diameter of GaN nanowires ranged from 20 nm to several hundreds of nm, and their length was about several tens of μm. The growth mechanism of GaN nanowires was discussed using a vapor–liquid–solid (VLS) model. Furthermore, room-temperature cathodoluminescence spectra of undoped and Zn-doped GaN nanowires showed emission peaks at 364 and 420 nm, respectively. 相似文献
13.
Thin-film GaAs on glass was formed by ablating n-type GaAs with nano-second pulses at 532 nm. The deposition was done in the most straightforward way without heating the substrate. The texture of films has been investigated with X-ray measurements, spatially resolved micro-Raman spectroscopy, and atomic force microscopy. The results reveal that the film texture is of multi-phase nature consisting of randomly oriented GaAs microcrystallites, amorphous parts, and (1 1 1) zincblende migrations in the nano-regime. 相似文献
14.
We report on the selective area growth (SAG) of GaN nanorods on Si substrates masked with W or SiO2 and also on bare Si substrates by RF plasma-assisted molecular beam epitaxy (RF-MBE). The growth of GaN (i.e. irradiation of Ga and RF plasma-activated N2) on the W mask layer results in the appearance of a ring reflection high-energy electron diffraction (RHEED) pattern coming from α-W. In contrast, broken ring RHEED patterns from GaN nanorods are clearly observed on SiO2 and Si surfaces. Ex-situ scanning Auger microscopy analysis confirms that no growth of GaN takes place on W. Utilizing this phenomenon, we have demonstrated the SAG of GaN nanorods on Si substrates partly masked with W. We will discuss this phenomenon in terms of the difference in the desorption energy of Ga on W, SiO2, and Si. 相似文献
15.
The molecular beam epitaxy (MBE) growth of GaAs and InAs quantum dots on etched mesas has been studied using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The [0 1 1]-oriented mesas are etched into (1 0 0) GaAs substrates, exposing (5 3 3)B sidewall facets. At a substrate temperature of 610 °C a top (1 0 0) plane is seen to evolve on a ridge mesa structure. Alternatively, if the overgrowth is carried out at 630 °C no such facet is seen, and the top ridge remains unchanged during GaAs growth. By controlling the mesa shape, either ordered lines of dots can be grown or the dot density can be varied from <5×108 cm−2 to >1×1011 cm−2 on the same substrate in pre-defined regions. The dot distribution observed on the mesa sidewalls and top is discussed in terms of net migration of adatoms from different facets, underlying step density, step height and surface curvature of the mesa top. 相似文献
16.
Urban Forsberg A. LundskogA. Kakanakova-Georgieva R. CiechonskiE. Janzén 《Journal of Crystal Growth》2009,311(10):3007-3010
The inherent advantages of the hot-wall metal organic chemical vapor deposition (MOCVD) reactor (low temperature gradients, less bowing of the wafer during growth, efficient precursor cracking) compared to a cold-wall reactor make it easier to obtain uniform growth. However, arcing may occur in the growth chamber during growth, which deteriorates the properties of the grown material. By inserting insulating pyrolytic BN (PBN) stripes in the growth chamber we have completely eliminated this problem. Using this novel approach we have grown highly uniform, advanced high electron mobility transistor (HEMT) structures on 4″ semi-insulating (SI) SiC substrates with gas-foil rotation of the substrate. The nonuniformities of sheet resistance and epilayer thickness are typically less than 3% over the wafer. The room temperature hall mobility of the 2DEG is well above 2000 cm2/V s and the sheet resistance about 270 Ω/sqr. 相似文献
17.
Qian Sun Yong Suk Cho Bo Hyun Kong Hyung Koun Cho Tsung Shine Ko Christopher D. Yerino In-Hwan Lee Jung Han 《Journal of Crystal Growth》2009,311(10):2948-2952
In this work, we report the growth of smooth, high-quality N-face GaN on c-plane sapphire by metalorganic chemical vapor deposition. It is found that the nitridation temperature of sapphire has a critical effect on the surface morphology of N-face GaN. Sapphire after a severe nitridation gives rise to a high density of hexagonal hillocks during N-face GaN growth. Smooth N-face GaN has been grown on appropriately nitridized sapphire. The N-polarity of the GaN film has been confirmed with no inversion domain by convergent beam electron diffraction. Controlled growth interruption is carried out to study the nucleation evolution during N-face GaN growth, which is found distinctly different from the two-step growth of Ga-face GaN. Atomically smooth N-face GaN has been achieved with comparable structural quality to Ga-face GaN. 相似文献
18.
Dabing Li Bei Ma Reina Miyagawa Weiguo Hu Mitsuhisa Narukawa Hideto Miyake Kazumasa Hiramatsu 《Journal of Crystal Growth》2009,311(10):2906-2909
Si-doped a-plane GaN films with different doping concentrations were grown by metal-organic vapor phase epitaxy. A mirrorlike surface without pits or anisotropic stripes was observed by optical microscopy. Detailed optical properties of the samples were characterized by temperature- and excitation-intensity-dependent PL measurements. A series of emission peaks at 3.487, 3.440, 3.375–3.350, 3.290 and 3.197 eV were observed in the low-temperature PL spectra of all samples. The origin of these emissions is discussed in detail. 相似文献
19.
C. Jiménez T. Caroff L. Rapenne S. Morlens E. Santos P. Odier F. Weiss 《Journal of Crystal Growth》2009,311(11):3204-3210
La2Zr2O7 (LZO) films have been grown by metalorganic decomposition (MOD) to be used as buffer layers for coated conductors. A characteristic feature of LZO thin films deposited by MOD is the formation of nanovoids in an almost single crystal structure of LZO pyrochlore phase. Annealing parameters (heating ramp, temperature, pressure, etc.) were varied to establish their influence on the microstructure of the LZO layers. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used for sample characterization. The epitaxial pyrochlore phase was obtained for annealing temperatures higher than 850 °C whatever the other annealing conditions. However, the film microstructure, in particular, nanovoids shape and size, is strongly dependent on heating ramp and pressure during annealing. When using low heating ramp, percolation of voids creates diffusion channels for oxygen which are detrimental for the substrate protection during coated conductor fabrication. From this point of view high heating rates are more adapted to the growth of LZO layers. 相似文献
20.
Admittance (Ym) versus applied gate bias (VG) on MIS structure (Cr/a-SiNx:H/p-Si) was measured as a function of frequency (mHz-MHz)/temperature (77-400 K) as parameters to investigate minority carrier behavior. Strong frequency dispersion in measured capacitance at inverting gate bias (positive biases for p-type silicon substrate) and low frequency behavior in capacitance-voltage (C-V) curves under high measuring frequencies (above kHz) at 300-400 K temperature interval are reported. This phenomenon is interpreted via lateral hopping conductivity of self-inversion charges beyond the gate inside a-SiNx:H film near interface as generation mechanism of minorities with a lower activation energy (0.11 eV) rather than prevailing mechanisms of much higher activation energies (namely, generation-recombination and diffusion). 相似文献