Growth and transport properties of InAs thin films on GaAs

High-quality InAs epitaxial layers have been grown on (1 0 0) oriented semi-insulating GaAs substrates by MBE. The transport properties of largely lattice mismatched InAs/GaAs heterojunctions have been investigated by Hall effect measurements down to 10 K. In spite of a high dislocation density at the heterointerface, very high electron mobilities are obtained in the InAs thin films. By doping Si into the layer far from the InAs/GaAs interface, we found that the doped samples have higher electron mobility than that of the undoped samples with the same thickness. The mobility demonstrates a pronounced minimum around 300 K for the undoped sample. But for Si-doped samples, no pronounced minimum has been found. Such abnormal behaviours are explained by the parallel conduction from the quasi-bulk carriers and interface carriers. These high-mobility InAs thin films are found to be suitable materials for making Hall elements. (C) 1998 Elsevier Science B.V. All rights reserved.

Raman scattering from In1-x-yGaxAlyAs quaternary alloys

Raman scattering studies were reported of In1-x-yGaxAlyAs/InP lattice matched quaternary alloys. The quaternary alloys a.ere grown on (100) oriented InP substrates by MBE method. The composition and intensity dependence of optical phonon mode frequencies show that the quaternary alloys exhibit three-mode behavior, i.e. InAs-like, GaAs-like and AlAs-like modes. Polarization analysis of the Raman spectra shows that the LO phonon modes are Raman active in the depolarized configuration and Raman inactive in the polarized configuration. TO phonon modes were also observed due to disorder effects, resulting in the asymmetrical shapes of the Raman peaks of the optical phonons.

Hydrogen-decorated lattice defects in proton implanted GaN

Several vibrational bands were observed near 3100 cm(-1) in GaN that had been implanted with hydrogen at room temperature and subsequently annealed, Our results indicate that these bands are due to nitrogen-dangling-bond defects created by the implantation that an decorated by hydrogen, The frequencies are close to those predicted recently for V-Ga-H-n complexes, leading us to tentatively assign the new lines to V-Ga defects decorated with different numbers of H atoms. (C) 1998 American Institute of Physics. [S0003-6951(98)03614-6].

High energy ion implantation enhanced intermixed quantum well structures and their absorption characteristics in passive optical waveguides

We have shown that high energy ion implantation enhanced intermixing (HE-IIEI) technology for quantum well (QW) structures is a powerful technique which can be used to blue shift the band gap energy of a QW structure and therefore decrease its band gap absorption. Room temperature (RT) photoluminescence (PL) and guided-wave transmission measurements have been employed to investigate the amount of blue shift of the band gap energy of an intermixed QW structure and the reduction of band gap absorption, Record large blue shifts in PL peaks of 132 nm for a 4-QW InGaAs/InGaAsP/InP structure have been demonstrated in the intermixed regions of the QW wafers, on whose non-intermixed regions, a shift as small as 5 nm is observed. This feature makes this technology very attractive for selective intermixing in selected areas of an MQW structure. The dramatical reduction in band gap absorption for the InP based MQW structure has been investigated experimentally. It is found that the intensity attenuation for the blue shifted structure is decreased by 242.8 dB/cm for the TE mode and 119 dB/cm for the TM mode with respect to the control samples. Electro-absorption characteristics have also been clearly observed in the intermixed structure. Current-Voltage characteristics were employed to investigate the degradation of the p-n junction in the intermixed region. We have achieved a successful fabrication and operation of Y-junction optical switches (JOS) based on MQW semiconductor optical amplifiers using HE-IIEI technology to fabricate the low loss passive waveguide. (C) 1997 Published by Elsevier Science B.V.

中国材料工程大典—信息功能材料工程

本书是《中国材料工程大典》中的卷目之一。 信息功能材料是信息科学技术和信息产业发展的基础和先导。21世纪将是以信息产业为核心的知识经济时代，对信息技术和信息资源的竞争将更加激烈。我国电子信息行业2004年完成产品销售收入达26500亿元，多年来已居外贸出口首位，并继续以高出工业发展速度10％的速度发展，已成为世界信息产业大国。加快由信息产业大国向信息产业强国迈进的步伐，是我们广大从事信息技术，特别是信息功能材料工作者义不容辞的责任。希望《中国材料工程大典》中《信息功能材料工程》卷的出版，将有力推动我国信息技术和信息产业的健康发展。 《信息功能材料工程》分上、中、下卷，共设20篇，约600万字。它涉及到信息的获取、传输、存储、显示和处理等主要技术用的材料与器件，是目前我国该领域比较完整的专业工具书。参加这部书编写的有中科院、高校和部分企业的专家教授近200名。参加编写的主要单位有中科院半导体研究所、中科院物理研究所、中科院微电子研究所、中科院上海精密光学机械研究所、中科院上海红外技术物理研究所、中科院长春应用化学研究所、中科院合肥固体物理所、南京大学、清华大学、西安理工大学、北京有色金属研究总院、武汉邮电科学研究院等。历时近3年完稿。由王占国、陈立泉、屠海令任主编并统稿。 本卷各篇不仅全面系统地反映了国外信息功能材料研究领域的现状、最新进展和发展趋势，而且也特别注重我国在该领域的研发和产业化方面取得的成果，力图使其具有实用性、先进性和权威性。本书适合于从事信息功能材料的科研工作者和工程技术人员查阅使用，也可供有关师生参考。

Observation of photogalvanic current for interband absorption in InN films at room temperature

The linear and circular photogalvanic effects have been observed in undoped InN films for the interband transition by irradiation of 1060 nm laser at room temperature. The spin polarized photocurrent depends on the degree of polarization, and changes its sip when the radiation helicity changes from left-handed to right-handed. This result indicates the sizeable spin-orbit interaction in the InN epitaxial layer and provides an effective method to generate spin polarized photocurrent and to detect spin-splitting effect in semiconductors with promising applications on spintronics.

Superluminescent diode monolithically integrated with novel Y-branch by bundle integrated waveguide for fiber optic gyroscope - art. no. 68380D

We have developed a novel InP-based, ridge-waveguide photonic integrated circuit (PIC), which consists of a 1.1-um wavelength Y-branch optical waveguide with low loss and improved far field pattern and a 1.3-um wavelength strained InGaAsP-InP multiple quantum-well superluminescent diode, with bundle integrated guide (BIG) as the scheme for monolithic integration. The simulations of BIG and Y-branches show low losses and improved far-field patterns, based on the beam propagation method (BPM). The amplified spontaneous emission of the device is up to 10 mW at 120 mA with no threshold and saturation. Spectral characteristics of about 30 nm width and less than I dB modulation are achieved using the built-in anti-lasing ability of Y-branch. The beam divergence angles in horizontal and vertical directions are optimized to as small as 12 degrees x8 degrees, resulting in good fiber coupling. The compactness, simplicity in fabrication, good superluminescent performance, low transmission loss and estimated low coupling loss prove the BIG and Y-branch method to be a feasible way for integration and make the photonic integrated circuit of Y-branch and superluminescent diode an promising candidate for transmitter and transceiver used in fiber optic gyroscope.

Native deep level defects in ZnO single crystal grown by CVT method - art. no. 68410I

Hall effect, photoluminescence (PL), infrared absorption, deep level transient spectroscopy (DLTS), and Raman scattering have been used to study property and defects of ZnO single crystal grown by a chemical vapor transport method (CVT). As-grown ZnO is N type with free electron density Of 10(16)-10(17)cm(-3). It has a slight increase after 900 degrees C annealing in oxygen ambient. The DLTS measurement revealed four deep level defects with energy at 0.30eV, 0.50eV, 0.68eV and 0.90eV in the as-grown ZnO sample, respectively. After the high temperature annealing, only the 0.5eV defect survive and has a concentration increase. PL results of the as-grown and annealed ZnO indicate that the well-known green emission disappear after the annealing. The result suggests a correlation between the 0.68eV defect and the green PL peak. Results of P-doped ZnO were also compared with the undoped ZnO sample. The nature of the defects and their influence on the material property have been discussed.

Growth of GaSb and GaInAsSb layers for thermophotovolatic cells by liquid phase epitaxy - art. no. 68411E

GaSb based cells as receivers in thermophotovoltaic system have attracted great interest and been extensively studied in the recent 15 years. Although nowadays the manufacturing technologies have made a great progress, there are still some details need to make a further study. In this paper, undoped and doped GaSb layers were grown on n-GaSb (100) substrates from both Ga-rich and Sb-rich solutions using liquid phase epitaxy (LPE) technique. The nominal segregation coefficients k of intentional doped Zn were 1.4 and 8.8 determined from the two kinds of GaSb epitaxial layers. Additionally, compared with growing from Ga-rich solutions, the growing processes from Sb-rich solutions were much easier to control and the surface morphologies of epitaxial layers were smoother. Further-more, in order to broaden the absorbing edge, Ga1-xInxAsySb1-y quaternary alloys were grown on both GaSb and InAs substrates from In-rich solutions, under different temperature respectively.

A New Edge-Coupled Two-Terminal Double Heterojunction Phototransistor (ECTT-DHPT) and Its DC Characteristics

A new ECTT-DHPT with InGaAsP(lambda=1.55 mu m) as base and InGaAsP(lambda=1.3 mu m) as collector as well as waveguide was designed and fabricated, the DC characteristics reveal that the ECTT-DRPT can perform good optoelectronic mix operation and linear amplification operation by optically biased at two appropriate value respectively. Responsivity of more than 52A/W and dark current of 70nA (when V-ce=1V) were obtained.

In-Situ Boron and Aluminum Doping and Their Memory Effects in 4H-SiC Homoepitaxial Layers Grown by Hot-Wall LPCVD

The in-situ p-type doping of 4H-SiC grown on off-oriented (0001) 4H-SiC substrates was performed with trimethylaluminum (TMA) and/or diborane (B2H6) as the dopants. The incorporations of Al and B atoms and their memory effects and the electrical properties of p-type 4H-SiC epilayers were characterized by secondary ion mass spectroscopy (SIMS) and Hall effect measurements, respectively. Both Al- and B-doped 4H-SiC epilayers were p-type conduction. It was shown that the profiles of the incorporated boron and aluminum concentration were in agreement with the designed TMA and B2H6 flow rate diagrams. The maximum hole concentration for the Al doped 4H-SiC was 3.52x10(20) cm(-3) with Hall mobility of about 1 cm(2)/Vs and resistivity of 1.6 similar to 2.2x10(-2) Omega cm. The heavily boron-doped 4H-SiC samples were also obtained with B2H6 gas flow rate of 5 sccm, yielding values of 0.328 Omega cm for resistivity, 5.3x10(18) cm(-3) for hole carrier concentration, and 7 cm(2)/VS for hole mobility. The doping efficiency of Al in SiC is larger than that of B. The memory effects of Al and B were investigated in undoped 4H-SiC by using SIMS measurement after a few run of doped 4H-SiC growth. It was clearly shown that the memory effect of Al is stronger than that of B. It is suggested that p-type 4H-SiC growth should be carried out in a separate reactor, especially for Al doping, in order to avoid the join contamination on the subsequent n-type growth. 4H-SiC PiN diodes were fabricated by using heavily B doped epilayers. Preliminary results of PiN diodes with blocking voltage of 300 V and forward voltage drop of 3.0 V were obtained.

Direct Wafer Bonding Technology employing vacuum-cavity pre-bonding

A novel low temperature direct wafer bonding technology employing vacuum-cavity pre-bonding is proposed and applied in bonding of InGaAs/Si couple wafers under 300 degrees C and InP/GaAs couple wafers under 350 degrees C. Aligning accuracy of 0.5 mu m is achieved. During wafer bonding process the pressure on the couple wafers is 10MPa. The interface energy is sufficiently high to allow thinning of the wafers down from 350um to about 100um. And the tensile strength test indicates the bonding energy of bonded samples is about equal to the bonded samples at 550 degrees C.

Investigations on oxide-free InGaAlAs waveguides grown by narrow stripe selective MOVPE

Oxide-free InGaAlAs waveguides have been grown on the InP substrates patterned with pairs of SiO2 mask stripes using narrow stripe selective MOVPE. The mask stripe width is varied from 0 to 40 pm, while the window region width between a pair of mask stripes is fixed at 1.5, 2.5 and 3.5 mu m, respectively. Smooth surface s and flat interfaces are obtained in the selectively grown InQaAlAs waveguides. There exhibit strong dependences of the thickness enhancement ratio and the photoluminescence (PL) spectrum on the mask stripe width and the window region width for the InGaAlAs wavegwdes. A large PL peak wavelength shift of 79 nm and a PL full width of at half maximum (FWHM) of less than 64 meV are obtained simultaneously. Some possible interpretations for our investigations are presented by considering both the migration effect from a masked region (MMR) and the lateral vapor diffusion effect (LVD).

Growth mechanism of InGaAlAs waveguides by narrow stripe selective MOVPE

Growth mechanism of InGaAlAs waveguides by narrow stripe selective MOVPE has been studied. Both the InGaAlAs bulk waveguides and the InGaAlAs MQW waveguides were successful grown on the patterned substrates at optimized growth conditions. The mask stripe width varied from 0 to 40 mu m, while the window region width between a pair of mask stripes was fixed 2.5 mu m. These selectively grown waveguides were covered by specific InP layers, which can keep the InGaAlAs waveguides from being oxidized during the fabrication of devices. In particular, there exhibit strong dependences of the photoluminescence (PL) spectrum on the mask stripe width for the samples. The results were explained in considering both the migration effect from a masked region (MMR) and the lateral vapor diffusion effect (LVD).

Heavily doped polycrystalline 3C-SiC growth on SiO2/Si(100) substrates for resonator applications

3C-SiC is a promising material for the development of microelectromechanical systems (MEMS) applications in harsh environments. This paper presents the LPCVD growth of heavily nitrogen doped polycrystalline 3C-SiC films on Si wafers with 2.0 mu m-thick silicon dioxide (SiO2) films for resonator applications. The growth has been performed via chemical vapor deposition using SiH4 and C2H4 precursor gases with carrier gas of H-2 in a newly developed vertical CVD chamber. NH3 was used as n-type dopant. 3C-SiC films were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), secondary ion mass spectroscopy (SIMS), and room temperature Hall Effect measurements. It was shown that there is no voids at the interface between 3C-SiC and SiO2. Undoped 3C-SiC films show n-type conduction with resisitivity, Hall mobility, and carrier concentration at room temperature of about 0.56 Omega center dot cm, 54 cm(2)/Vs, and 2.0x 10(17) cm(-3), respectively. The heavily nitrogen doped polycrystalline 3C-SiC with the resisitivity of less than 10(-3) Omega center dot cm was obtained by in-situ doping. Polycrystalline SiC resonators have been fabricated preliminarily on these heavily doped SiC films with thickness of about 2 mu m. Resonant frequency of 49.1 KHz was obtained under atmospheric pressure.