共查询到20条相似文献,搜索用时 15 毫秒
1.
Shuji Nakamura 《Materials Science and Engineering: B》1997,50(1-3):277-284
The continuous-wave operation of InGaN multi-quantum-well (MQW) structure laser diodes (LDs) was demonstrated at room temperature with a threshold current of 25 mA, a threshold voltage of 5.8 V, an output power of 30 mW and a high operating temperature of 100°C. The energy differences between the absorption and the emission energy of the InGaN MQW structure LDs were as large as 220 meV at RT. A deep localized state (the localization energy is >100 meV) was formed in the InGaN well layer due to the InGaN phase separation during the growth. Both the spontaneous emission and the stimulated emission of the LDs originated from these deep localized energy states. The far field pattern showed a higher order transverse mode of the entire 5-μm-thick epitaxial layer stack, with air and sapphire as the upper and lower cladding layers, respectively. 相似文献
2.
K Eberl M Lipinski Y.M Manz N.Y Jin-Phillipp W Winter C Lange O.G Schmidt 《Thin solid films》2000,380(1-2):183-188
Stranski–Krastanov growth in molecular beam epitaxy allows the preparation of self assembling InAs and InP quantum dots on GaAs and Ga0.52In0.48P buffer layers, respectively. InAs dots in GaAs prepared by slow growth rates and low temperature overgrowth provide intense photoluminescence at the technologically important wavelength of 1.3 μm at room temperature. Strain induced vertical alignment, size modification and material interdiffusion for stacked dot layers are studied. A blue shift of the ground state transition energy is observed for the slowly deposited stacked InAs dots. This is ascribed to enhanced strain driven intermixing in vertically aligned islands. For very small densely stacked InP and InAs dots the reduced confinement shift causes a red shift of the ground state emission. The InP quantum dots show intense and narrow photoluminescence at room temperature in the visible red spectral range. First InP/Ga0.52In0.48P quantum dot injection lasers are prepared using threefold stacked InP dots. We observe lasing at room temperature in the wavelength range between 690–705 nm depending on the size of the stacked InP dots. 相似文献
3.
V. P. Mikhailov N. V. Kuleshov N. I. Zhavoronkov P. V. Prokohsin K. V. Yumashev
V. A. Sandulenko
《Optical Materials》1993,2(4):267-272The saturation of the optical absorption in V3+ : YAG crystal is investigated. The absorption cross section of tetrahedral V3+ at 1.08 μm is estimated to be 8.2±2.5x10-18 cm2. Q-switching and passive mode-locking for a number of solid state lasers with wavelengths at 747 nm, 780 nm, 1.06 μm and 1.34 μm have been obtained with a V3+ :YAG saturable absorber. 相似文献
4.
D. A. Livshits A. R. Kovsh A. E. Zhukov N. A. Maleev S. S. Mikhrin A. P. Vasil’ev E. V. Nikitina V. M. Ustinov N. N. Ledentsov G. Lin J. Chi 《Technical Physics Letters》2004,30(1):9-11
Single-mode lasers operating in the 1.3 μ m wavelength range have been obtained with the active region based on InAs/AlGaAs/GaAs quantum dot heterostructures. A minimum threshold current of about 1.4 mA is reached, which is a record value for ridge waveguide lasers. The maximum efficiency and maximum output power in the cw lasing mode are 0.73 W/A and 120 mW, respectively. 相似文献
5.
Ying-Chih Chen Chun-Yuan Huang Yan-Kuin Su Wen-Liang Li Chia-Hsien Yeh Yu-Cheng Lin 《Nanotechnology, IEEE Transactions on》2008,7(4):503-507
6.
Moreau G. Merghem K. Martinez A. Bouchoule S. Ramdane A. Grillot F. Piron R. Dehease O. Homeyer E. Tavernier K. Loualiche S. Berdaguer P. Pommerau F. 《Optoelectronics, IET》2007,1(6):255-258
The achievement of a 1.51 mum InAs/InP(3 11)B quantum dot (QD) single-mode Fabry-Perot laser operating under continuous wave at room temperature is reported. A threshold current of 80 mA associated with a 0.12 W/A external efficiency is reported for as-cleaved device at room temperature. The maximum output power, the gain peak wavelength at threshold and the full width at half maximum of the spectral gain are 5 mW, 1512 nm and 60 nm, respectively. Although these performances must be improved in the future, these results constitute to our knowledge the state-of-the-art on InP(3 1 1)B substrate. These results are of great interest since QD-based lasers are expected to play a major role in the next generation telecommunication networks as low-cost devices. 相似文献
7.
W. Braunschweig W. Karpinski Th. Kubicki K. Lü belsmeyer J. Ortmanns D. Pandoulas G. Pierschel C. Rente R. Siedling O. Syben F. Tenbusch M. Toporowsky Th. Wilms B. Wittmer W. J. Xiao 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》1996,370(2-3):377-380
A microstrip gallium arsenide detector (thickness 508 μm, strip width 100 μm, strip pitch and readout pitch 200 μm) has been tested in a 50 GeV/c electron beam at CERN. Using the low noise Viking preamplifier chip (shaping time 1.5 μs) signal to noise ratios up to 25 were measured depending on bias voltage and angle of incidence. Applying the so-called η-algorithm (using the impact position-sensitive charge sharing between adjacent strips) a resolution down to σ 20 μm could be obtained. 相似文献
8.
G. E. Cirlin N. K. Polyakov V. N. Petrov V. A. Egorov D. V. Denisov B. V. Volovik V. M. Ustinov Zh. I. Alferov N. N. Ledentsov R. Heitz D. Bimberg N. D. Zakharov P. Werner U. Gsele 《Materials Science and Engineering: B》2001,80(1-3):108-111
MBE growth and properties of InAs nanoscale islands formed on silicon are reported. Islands capped with Si emit a photoluminescence band in the 1.3 μm region. Upon annealing at increased substrate temperature, extensive interdiffusion leads to the formation of an InAs solid solution in the Si cap layer. Additionally, InAs-enriched regions with extensions of 6 nm, exhibiting two kinds of ordering, are observed. The ordering of InAs molecules occurs, respectively, in (101) and
planes inclined to (110) and
planes parallel to the [001] growth direction. 相似文献
9.
Thin near-stoichiometric silica films were deposited by plasma-enhanced chemical vapour deposition (PECVD) using pure SiH4 and O2 in a planar plasma reactor based on the proprietary uniform distributed electron cyclotron resonance (UDECR) technology. Samples were kept approximately at room temperature during the process. In the pressure range 0.1–0.4 Pa, dense ( > 5 × 1010 cm−3) diffusion plasmas could be sustained very homogeneously over areas larger than 200 mm× 200 mm. In conjunction with appropriate distributed gas injection set-up, extremely good layer uniformities were obtained, with no visible irisations for thicknesses of 0.1–6 μm. The reactor concept intrinsically lends itself to process scale-up which is even trivial along one dimension. The effects of gas flow rates and substrate r.f. bias were investigated, mainly by Fourier transform infrared absorption spectroscopy and spectroscopic ellipsometry (1.4–5.0 eV). The Si-H and O-H bond contents were found to be very low for all samples. For films deposited under sufficient ion bombardment energy, typical values for the refractive index at 2.0 eV (1.458) and the Si-O-Si stretching frequency (1075 cm−1) were very close to those obtained in the case of thermally grown silica, indicating an unusually dense microstructure for the as-deposited PECVD films grown at quasi-ambient temperature.
Transparent protective coatings 3–5 μm thick showing excellent abrasion resistance and weatherability could thus be deposited on metals and optical polymers. 相似文献
10.
F-2 color center in LiF crystals is a unique specie of color centers concerning its photothermal stability, its broad absorption band, centered at 0.96 μm, and its broad emission band peaking at 1.12 μm, being a tunable laser operating in the range from 1.08 μm to 1.22 μm. The luminescence quantum efficiency of the main transition in the laser optical cycle was determined, at room temperature, and its value is 0.5 ± 0.1. This value was obtained using a method correlating the absorption, excitation and photoacoustic spectra. Besides, the luminescence quantum efficiency of the fundamental transition of the F-3 color center was determined. Also was estimated the energy transfer efficiency due to the overlapping of the F-3 center emission and the F-2 center absorption bands. Possible nonradiative deexcitation mechanisms accounting for the small luminescence quantum efficiency of the F-2 color centers in LiF are also discussed. 相似文献
11.
Molecular beam epitaxy growth methods of wavelength control for InAs/(In)GaAsN/GaAs heterostructures
We discuss the molecular beam epitaxy (MBE) growth methods of emission wavelength control and property investigations for different types of InAs/(In)GaAsN/GaAs heterostructures containing InGaAsN quantum-size layers: (1) InGaAsN quantum wells deposited by the conventional mode in a GaAs matrix, (2) InAs quantum dots deposited in a GaAsN matrix or covered by an InGaAs(N) layer, and (3) InAs/InGaAsN/GaAsN strain-compensated superlattices with quantum wells and quantum dots. The structures under investigation have demonstrated photoluminescence emission in a wavelength range of ~1.3-1.8?μm at room temperature without essential deterioration of the radiative properties. 相似文献
12.
Based on an optimized bonding technique for semiconductor lasers, parametric investigations of different bonding configurations were performed using AuSn solder. No abrupt electrical degradation was observed for both face-up and face-down bonding configurations. The typical optical output achieved for face-up and face-down bonding approach was about 100 mW/facet and 150 mW/facet, respectively. Face-up bonded LDs exhibited a steady differential quantum efficiency ηD of ∼ 0.425 mW/mA before gradual degradation at 200 mA, while face-down bonded LDs improved its performance beyond 350 mA. The characteristic temperature T0 also improved to as much as 643 K for face-down bonded LDs. Spectrally-resolved emission measurement showed that the temperature rise in unbonded, face-up bonded and face-down bonded LDs were approximately 11, 7-8 and 2-3 °C, respectively. These investigations showed that the improved performances for face-down bonding approach compared to face-up approach were due to better thermal management. 相似文献
13.
J. Rihani N. Ben Sedrine V. Sallet J.C. Harmand M. Oueslati R. Chtourou 《Materials science & engineering. C, Materials for biological applications》2008,28(5-6):918-922
InAs(Sb) quantum dots (QDs) samples were grown on GaAs (001) substrate by Molecular Beam Epitaxy (MBE). The structural characterization by Atomic Force Microscopy (AFM) of samples shows that InAsSb islands size increases strongly with antimony incorporation in InAs/GaAs QDs and decreases with reducing the growth temperature from 520 °C to 490 °C. Abnormal optical behaviour was observed in room temperature (RT) photoluminescence (PL) spectra of samples grown at high temperature (520 °C). Temperature dependent PL study was investigated and reveals an anomalous evolution of emission peak energy (EPE) of InAsSb islands, well-known as “S-inverted curve” and attributed to the release of confined carriers from the InAsSb QDs ground states to the InAsSb wetting layer (WL) states. With only decreasing the growth temperature, the S-inverted shape was suppressed indicating a fulfilled 3D-confinement of carriers in the InAsSb/GaAs QD sample. 相似文献
14.
以采用水热法制备的BaTiO3粉体作为原料, 利用普通烧结法和两步烧结法制备出晶粒尺寸为0.25~10.15 μm的BaTiO3陶瓷, 研究了晶粒尺寸效应对BaTiO3陶瓷的介电、压电以及铁电性能的影响。结果表明: BaTiO3陶瓷的四方相含量随着陶瓷晶粒尺寸的增大而增加; 当晶粒尺寸在1 μm以上时, 室温相对介电常数(ε° )和压电系数(d33)随着晶粒尺寸的减小而增大, 并在晶粒尺寸为1.12 μm时分别达到最大值5628和279 pC/N, 然后两者随着晶粒尺寸的进一步减小而迅速下降。BaTiO3陶瓷的剩余极化强度Pr随晶粒尺寸的增大而提高, 而矫顽场Ec却呈现出相反的趋势。晶粒尺寸对介电性能和压电性能的影响是由于90°电畴尺寸和晶界数量的变化。晶粒的晶体场和晶粒表面钉扎作用的变化影响了电畴, 进而改变电滞回线。 相似文献
15.
H. Çakmak Engin Arslan M. Rudziński P. Demirel H. E. Unalan W. Strupiński R. Turan M. Öztürk E. Özbay 《Journal of Materials Science: Materials in Electronics》2014,25(8):3652-3658
This study focuses on both epitaxial growths of InxGa1?xN epilayers with graded In content, and the performance of solar cells structures grown on sapphire substrate by using metal organic chemical vapor deposition. The high resolution X-ray and Hall Effect characterization were carried out after epitaxial InGaN solar cell structures growth. The In content of the graded InGaN layer was calculated from the X-ray reciprocal space mapping measurements. Indium contents of the graded InGaN epilayers change from 8.8 to 7.1 % in Sample A, 15.7–7.1 % in Sample B, and 26.6–15.1 % in Sample C. The current voltage measurements of the solar cell devices were carried out after a standard micro fabrication procedure. Sample B exhibits better performance with a short-circuit current density of 6 mA/cm2, open-circuit voltage of 0.25 V, fill factor of 39.13 %, and the best efficiency measured under a standard solar simulator with one-sun air mass 1.5 global light sources (100 mW/cm2) at room temperature for finished devices was 0.66 %. 相似文献
16.
采用相转化流延一步制备了NiO-Zr0.84Y0.16O2-δ (YSZ)阳极支撑层和功能层, 前者厚度为~700 μm, 含有沿厚度方向定向排列的开放直孔, 后者厚度为~60 μm。采用浆料涂膜法和高温共烧在阳极上制备厚度为15 μm的YSZ电解质薄膜, 丝网印刷制备YSZ-La0.84Sr0.16MnO3-δ (LSM)(质量比50:50)阴极。所制备的单电池显示出较高的电输出性能。以H2-3%H2O为燃料和环境空气为氧化剂, 800 ℃时电池的峰功率密度达到891 mW/cm2, 电池即使在高电流密度测试条件下也未出现明显的浓差极化, 这是由于其阳极具有开放直孔结构, 气相输运阻力小。 相似文献
17.
Er3+- and Yb3+- ions-co-doped silica thin films were prepared by RF magnetron sputtering. Enhanced photoluminescence centered at 1.534 μm was detected at room temperature when excited by a Nd–YAG laser line at 1.064 μm. The photoluminescence intensity increases with Yb-atom doped concentration and tends to saturate at the Yb-atom concentration of 3.0%, indicating that the enhanced photoluminescence results from the energy transfer from Yb3+ to Er3+. 相似文献
18.
R. M. Biefeld A. A. Allerman S. R. Kurtz E. D. Jones I. J. Fritz R. M. Sieg 《Journal of Materials Science: Materials in Electronics》2002,13(11):649-657
We describe the metal-organic chemical vapor deposition (MOCVD) growth of InAsSb/InAs and GaAsSb/GaAs(P) multiple quantum well (MQW) and InAsSb/InAsP and InAsSb/InPSb strained-layer superlattice (SLS) active regions for use in mid-infrared emitters. We also describe the growth and initial characterization of GaAsSbN/GaAs MQW structures. By changing the layer thickness and composition of the InAsSb SLSs and MQWs, we have prepared structures with low temperature (<20 K) photoluminescence wavelengths ranging from 3.2 to 6.0 m. We have made gain-guided, injection lasers using undoped, p-type AlAs0.16Sb0.84 for optical confinement and both strained InAsSb/InAs MQW and InAsSb/InAsP and InPSb SLS active regions. The lasers and LEDs utilize the semi-metal properties of a p-GaAsSb/n-InAs heterojunction as a source for electrons injected into the active regions. Cascaded, semi-metal, mid-infrared, injection lasers with pseudomorphic InAsSb multiple quantum well active region lasers and LEDs are reported. We also report on GaAsSb/GaAs(P) lasers and LEDs emitting at 1.1 to 1.2 m grown on GaAs substrates and using AlGaAs layers for confinement. 相似文献
19.
R. Beccard H. Protzmann M. Luenenbuerger B. Schineller M. Heuken 《Materials Science and Engineering: B》2001,80(1-3):50-53
We present results obtained from a 2400G3HT reactor with a maximum wafer capacity of 8×3 inch. To achieve uniformity of the growth, we increased the temperature uniformity on each satellite to 0.9°C and that from satellite to satellite to 0.8°C. The optimum reactor geometry has been found by extensive modeling of the reactor design. Thus, an optimization of uniformity and efficiency has been achieved. GaN, InGaN/GaN multi quantum wells, GaN:Si, GaN:Mg and AlGaN were obtained on 5×3 inch substrates by simple scaling of the corresponding process parameters of the 6×2 inch configuration. We demonstrate GaN:Si and GaN:Mg doping uniformity with a standard deviation of less than 5%, with thickness uniformities of less than 1.7% standard deviation without any edge exclusion. InGaN/GaN, quantum well emission at 480 nm shows a standard deviation of 1–2% without rim exclusion. We grew AlGaN with about 10% Al content and less than 2% standard deviation in Al composition across the 3 inch substrate. Simple electroluminescence test structures, consisting of a GaN:Si buffer, followed by a five-period InGaN/GaN quantum well and covered by a GaN:Mg cap with emission wavelengths of about 460 nm show wavelength variations across 3 inch wafers of less than 3 nm. All these results demonstrate that the AIXTRON Planetary Reactor® is a very flexible tool for mass production application, especially with respect to upgrading the system to larger wafer diameters, as is already well known from the standard GaAs and InP applications that are available up to 5×8 inch configurations. 相似文献
20.
Yu. S. Oseledchik A. I. Pisarevsky A. L. Prosvirnin V. V. Starshenko N. V. Svitanko 《Optical Materials》1994,3(4):237-242
Refractive indices of flux grown RbTiOPO4 (RTP) were measured in the wavelength interval 0.406 to 1.064 μm and Sellmeier equation coefficients were calculated. Phase-matching curves for second harmonic generation from radiation with wavelengths of 1.064 μm and 1.079 μm were obtained. RTP nonlinear optical properties are compared to those of KTP. Second-harmonic generation in RTP crystal is carried out with the efficiency of 65%. 相似文献