共查询到20条相似文献,搜索用时 0 毫秒
1.
Tang Ning Shen Bo Wang Maojun Yang Zhijian Xu Ke Zhang Guoyi Gui Yongsheng Zhu Bo Guo Shaoling Chu Junhao 《半导体学报》2006,27(2):235-238
在低温和强磁场下,通过磁输运测量研究了不同Al组分调制掺杂AlxGa1-xN/GaN异质结二维电子气(2DEG)的磁电阻振荡现象.观察到低Al组分异质结中的2DEG有较低的浓度和较高的迁移率. 相似文献
2.
利用X射线光电子能谱(XPS)对苝四甲酸二酐[3,4,9,10-perylenetetracarboxylic dianhydride(PTCDA)]/铟锡氧化物(ITO)表面和界面进行了研究.用原子力显微镜(AFM)对PTCDA/ITO样品的表面形貌进行了分析.XPS表明,在原始表面的C1s精细谱存在两个主谱峰和一个伴峰,主谱峰分别由结合能为284.6eV的苝环中的C原子和结合能为288.7eV的酸酐基团中的C原子激发;而结合能为290.4eV的伴峰的存在,说明发生了来源于ITO膜中的氧对C原子的氧化现象.O原子在C=O键和C-O-C键的结合能分别为531.5和533.4eV.在界面处,C1s谱中较高结合能峰消失,且峰值向低结合能方向发生0.2eV的化学位移;O1s谱向低结合能方向发生1.5eV的化学位移.由此可以推断,在界面处PTCDA与ITO的结合是PTCDA中的苝环与ITO中的In空位的结合.AFM的结果显示,PTCDA薄膜为岛状结构,岛的直径约为100~300nm,表面起伏约为14nm.相邻两层PTC-DA分子由于存在离域大π键而交叠和PTCDA分子中的苝环与ITO的In空位的紧密结合是最终导致PTCDA岛状结构形成的原因. 相似文献
3.
4.
M. A. L. Johnson Shizuo Fujita W. H. Rowland W. C. Hughes Y. W. He N. A. El-Masry J. W. Cook J. F. Schetzina J. Ren J. A. Edmond 《Journal of Electronic Materials》1996,25(5):793-797
The growth of GaN and AlGaN by molecular beam epitaxy (MBE) has been studied using GaN/SiC substrates. The GaN/SiC substrates
consisted of ∼3 μm thick GaN buffer layers grown on 6H-SiC wafers by metalorganic vapor phase epitaxy (MOVPE) at Crée Research,
Inc. The MBE-grown GaN films exhibit excellent structural and optical properties—comparable to the best GaN grown by MOVPE.
AlxGa1−xN films (x ∼ 0.06-0.08) and AlxGa1−xN/GaN multi-quantum-well structures which display good optical properties were also grown by MBE on GaN/SiC substrates. 相似文献
5.
肖特基C-V法研究Al_xGa_(1-x)N/GaN异质结界面二维电子气 总被引:2,自引:2,他引:0
通过对 Pt/ Al0 .2 2 Ga0 .78N/ Ga N肖特基二极管的 C- V测量 ,研究分析了 Al0 .2 2 Ga0 .78N/ Ga N异质结界面二维电子气 (2 DEG)浓度及其空间分布 .测量结果表明 ,Al0 .2 2 Ga0 .78N/ Ga N异质结界面 2 DEG浓度峰值对应的深度在界面以下 1.3nm处 ,2 DEG分布峰的半高宽为 2 .3nm ,2 DEG面密度为 6 .5× 10 1 2 cm- 2 .与 Alx Ga1 - x As/ Ga As异质结相比 ,其 2 DEG面密度要高一个数量级 ,而空间分布则要窄一个数量级 .这主要归结于 Alx Ga1 - x N层中~ MV / cm量级的压电极化电场和自发极化电场对 Alx Ga1 - x N/ Ga N异质结能带的调制和 Alx Ga1 - 相似文献
6.
Optimum conditions are reported for the growth of high-quality AlxGa1_xAs by means of vapor phase epitaxy from organometallic compounds (OMVPE). Typical values of mobili-ty and radiative recombination efficiency are reported, showing that OMVPE material quality is the same as that grown by liquid phase epitaxy (LPE). OMVPE-grown DH narrow-stripe lasers with Al.06Ga.94As active layers show minimum threshold currents of85 mÅ, comparable to the best lasers with similar structures produced by LPE. 相似文献
7.
Tong Zhang Y. Hwang J. Sun N. V. Edwards R. M. Kolbas P. J. Caldwell 《Journal of Electronic Materials》1993,22(9):1137-1140
Sharp erbium-related intra-4f shell luminescence from Er doped GaAs and Al0.4Ga0.6 As epitaxial layers grown by molecular beam epitaxy (MBE) is presented. The emission arising from the two Er3+ excited states,4I13/2 and4I11/2 are studied. We have observed, by means of heat treatment under differentambients such as As, Ga and Al over pressure, that
the optically active Er3+ preferentially occupies a Column III lattice site or Column III related defects. The photoluminescence results of co-doping
Al0.4Ga0.6As:Er with Si and Be by MBE is also reported for the first time. A strong single 1.54 μm spontaneous emission line is achieved
by co-doping with Be (≈1×1018 cm−3). This improvement is a result of successfully eliminating or suppressing the other transitions without sacrificing the 1.54
μm emission intensity or linewidth. 相似文献
8.
应用透射式电子显微镜观察了GaAs-AlxGa1-xAs多层异质结结构中的“精细低维调制条纹”。在邻近GaAs-AlxGa1-xAs超晶格层的缓冲层中和与这缓冲层邻近的GaAs-AlxGa1-xAs超晶格层的小区域中发现了等宽度的“精细低维调制条纹”,其宽度为9.1Å的GaAs条纹,12Å的AlxGa1-xAs条纹。文中介绍了用显微密度计获得的这些条纹的密度分布结果。同时还给出了GaAs-AlxGa1-xAs 多层异质结结构的晶格像和用X射线能量散射谱技术获得的成分定量分析结果。 相似文献
9.
L. J. Guido W. E. Plano D. W. Nam N. Holonyak J. E. Baker R. D. Burnham P. Gavrilovic 《Journal of Electronic Materials》1988,17(1):53-56
Data are presented demonstrating that the surface encapsulant and the As4 overpressure strongly affect Si diffusion in GaAs and AlxGa1-xAs, and thus are important parameters in impurity-induced layer disordering. Increasing As4 overpressure results in anincrease in diffusion depth in the case of GaAs, and adecrease in diffusion depth for AlxGa1-xAs. In addition, the band-edge exciton is observed in absorption on an AlxGa1-xAs-GaAs superlattice that is diffused with Si and is converted to bulk crystal AlyGa1-yAs via impurity-induced layer disordering. In contrast, the exciton is not observed in absorption on GaAs diffused with Si
in spite of the high degree of compensation. These data indicate that the Si diffusion process, and the properties of the
diffused material, are different for GaAs and for AlxGa1-xAs-GaAs superlattices converted into uniform AlyGa1-yAs (0 ≤y ≤x ≤ 1) via impurity-induced layer disordering with the amphoteric dopant Si. 相似文献
10.
F. A. Kish . J. Caracci N. Holonyak K. C. Hsieh J. E. Baker S. A. Maranowski A. R. Sugg J. M. Dallesasse R. M. Fletcher C. P. Kuo T. D. Osentowski M. G. Craford 《Journal of Electronic Materials》1992,21(12):1133-1139
Data are presented demonstrating the formation of native oxides from high Al composition In0.5(AlxGa1-x)0.5P (x≳ 0.9) by simple annealing in a “wet” ambient. The oxidation occurs by reaction of the high Al composition crystal with
H2O vapor (in a N2 carrier gas) at elevated temperatures (≥500° C) and results in stable transparent oxides. Secondary ion mass spectrometry
(SIMS) as well as scanning and transmission electron microscopy (SEM and TEM) are employed to evaluate the oxide properties,
composition, and oxide-semiconductor interface. The properties of native oxides of the In0.5(AlxGa1-x)0.5P system are compared to those of the AlxGa1-xAs system. Possible reaction mechanisms and oxidation kinetics are considered. The In0.5(AlxGa1-x)0.5P native oxide is shown to be of sufficient quality to be employed in the fabrication of stripe-geometry In0.5(AlxGa1-x)0.5P visible-spectrum laser diodes. 相似文献
11.
J. Zou B. F. Usher D. J. H. Cockayne R. Glaisher 《Journal of Electronic Materials》1991,20(7):855-859
The critical thicknesses of InxGa1-xAs/GaAs and GaAs/InxGa1-xAs/GaAs strained-layer systems were determined by transmission electron microscopy using the lift-off technique. The onset
of misfit dislocation generation has been observed for the first time and the geometries of the misfit dislocations in both
uncapped and capped layers correspond to the predicted models. A comparison is given between the predicted and experimental
critical thicknesses. 相似文献
12.
M. D. Bremser W. G. Perry O. H. Nam D. P. Griffis R. Loesing D. A. Ricks R. F. Davis 《Journal of Electronic Materials》1998,27(4):229-232
Thin films of Si-doped AlxGa1−xN (0.03≤x≤0.58) having smooth surfaces and strong near-band edge cathodoluminescence were deposited at 0.35–0.5 μm/h on on-axis
6H-SiC(0001) substrates at 1100°C using a 0.1 μm AlN buffer layer for electrical isolation. Alloy films having the compositions
of Al0.08Ga0.92N and Al0.48Ga0.52N exhibited mobilities of 110 and 14 cm2/V·s at carrier concentrations of 9.6×1018 and 5.0×1017 cm−3, respectively. This marked change was due primarily to charge scattering as a result of the increasing Al concentration in
these random alloys. Comparably doped GaN films grown under similar conditions had mobilities between 170 and ∼350 cm2/V·s. Acceptor doping of AlxGa1−xN for x≤0.13 was achieved for films deposited at 1100°C. No correlation between the O concentration and p-type electrical
behavior was observed. 相似文献
13.
The origin of the abrupt decrease withx both in electron concentration and in mobility of AlxGa1−xN in the range ofx between 0.4 and 0.6 was investigated by photoluminescence from epitaxial layers covering the entire range of alloy composition.
Band edge luminescence from undoped layers was observed out to anx value of 0.75. Whenx was larger than 0.2, a peak 0.2–0.5 eV below the band edge peak was also observed both from undoped and from Zn doped samples.
This is tentatively ascribed to an unidentified acceptor (or acceptors) related to the presence of Al. No luminescence which
could be attributed to a deep native donor defect was observed in semi-insulating AlxGa1−xN layers. When Zn was added in the lowx range of the alloys, a broad band 0.5–0.8 eV below the band edge peak was observed as well as a relatively narrow peak. 相似文献
14.
In order to better understand the electrical and optical properties of GaAs and AlxGa1-x As used in making double heterojunction lasers, we have studied the Hall coefficient, resistivity and photoluminescence behavior
of doped epitaxial samples of these materials. In particular, we report results on Ge-doped GaAs and Alx Ga1-x As, Sn-doped AlxGa1-x As and Si-Te-doped GaAs single crystal layers which were grown on GaAs substrates by the liquid phase epitaxial method. The
effects of impurities in the solution on the carrier concentration, mobility, photoluminescence spectra and possible recombination
processes in these layers are discussed. 相似文献
15.
The temperature dependence of capacitance-voltage (C-V) and the conductance-voltage (G/w-V) characteristics of (Ni/Au)/Al0.3Ga0.7N/AlN/GaN heterostructures were investigated by considering the effect of series resistance (Rs) and interface states Nss in a wide temperature range (79-395 K). Our experimental results show that both Rs and Nss were found to be strongly functional with temperature and bias voltage. Therefore, they affect the (C-V) and (G/w-V) characteristics. The values of capacitance give two peaks at high temperatures, and a crossing at a certain bias voltage point (∼3.5 V). The first capacitance peaks are located in the forward bias region (∼0.1 V) at a low temperature. However, from 295 K the second capacitance peaks appear and then shift towards the reverse bias region that is located at ∼−4.5 V with increasing temperature. Such behavior, as demonstrated by these anomalous peaks, can be attributed to the thermal restructuring and reordering of the interface states. The capacitance (Cm) and conductance (G/w-V) values that were measured under both reverse and forward bias were corrected for the effect of series resistance in order to obtain the real diode capacitance and conductance. The density of Nss, depending on the temperature, was determined from the (C-V) and (G/w-V) data using the Hill-Coleman Method. 相似文献
16.
M. Razeghi M. A. Poisson J. P. Larivain J. P. Duchemin 《Journal of Electronic Materials》1983,12(2):371-395
The low pressure metalorganic chemical vapor deposition epitaxial growth and characterization of InP, Ga0.47In0.53 As and GaxIn1-xAsyP1-y, lattice-matched to InP substrate are described. The layers were found to have the same etch pit density (EPD) as the substrate.
The best mobility obtained for InP was 5300 cm2 V−1S−1 at 300 K and 58 900 cm2 V−1 S−1 at 772K, and for GaInAs was 11900 cm2 V−1 S−1 at 300 K, 54 600 cm2 V−1 S−1 at 77 K and 90 000 cm V−1S−1 at 2°K. We report the first successful growth of a GaInAs-InP superlattice and the enhanced mobility of a two dimensional
electron gas at a GaInAs -InP heterojunction grown by LP-MO CVD. LP MO CVD material has been used for GaInAsPInP, DH lasers
emitting at 1.3 um and 1.5 um. These devices exhibit a low threshold current, a slightly higher than liquid phase epitaxy
devices and a high differential quantum efficiency of 60%. Fundamental transverse mode oscillation has been achieved up to
a power outpout of 10 mW. Threshold currents as low as 200 mA dc have been measured for devices with a stripe width of 9 um
and a cavity length of 300 um for emission at 1.5 um. Values of T in the range 64–80 C have been obtained. Preliminary life
testing has been carried out at room temperature on a few laser diodes (λ = 1.5μm). Operation at constant current for severalthousand
hours has been achieved with no change in the threshold current. 相似文献
17.
The dielectric properties and AC electrical conductivity (σac)of the (Ni/Au)/Al0.22Ga0.78N/AlN/GaN heterostructures, with and without the SiNx passivation, have been investigated by capacitance-voltage and conductance-voltage measurements in the wide frequency (5kHz-5 MHz) and temperature (80-400 K) range. The experimental values of the dielectric constant (ε′), dielectric loss (ε′′), loss tangent (tanδ), σac and the real and imaginary part of the electric modulus (M′ and M′′) were found to be a strong function of frequency and temperature. A decrease in the values of ε′ and ε′′ was observed, in which they both showed an increase in frequency and temperature. The values of M′ and M′′ increase with increasing frequency and temperature. The σac increases with increasing frequency, while it decreases with increasing temperature. It can be concluded, therefore, that the interfacial polarization can occur more easily at low frequencies and temperatures with the number of interface states density located at the metal/semiconductor interface. It contributes to the ε′ and σac. 相似文献
18.
Simulation studies are carried out on the large signal and noise properties of heterojunction (HT) AlxGa1-xAs/GaAs double drift region (DDR) IMPATT devices at V-band (60 GHz). The dependence of Al mole fraction on the aforementioned properties of the device has been investigated. A full simulation software package has been indigenously developed for this purpose. The large signal simulation is based on a non-sinusoidal voltage excitation model. Three mole fractions of Al and two complementary HT DDR structures for each mole fraction i.e., six DDR structures are considered in this study. The purpose is to discover the most suitable structure and corresponding mole fraction at which high power, high efficiency and low noise are obtained from the device. The noise spectral density and noise measure of all six HT DDR structures are obtained from a noise model and simulation method. Similar studies are carried out on homojunction (HM) DDR GaAs IMPATTs at 60 GHz to compare their RF properties with those of HT DDR devices. The results show that the HT DDR device based on N-AlxGa1-xAs/p-GaAs with 30% mole fraction of Al is the best one so far as large signal power output, DC to RF conversion efficiency and noise level are concerned. 相似文献
19.
利用超高真空化学气相沉积(UHV/CVD)成功实现了Si1-xGex的低温选择性外延生长,并研究了H2对选择性外延生长的影响及其作用机理. 以SiH4和GeH4为反应气源,在开有6mm×6mm窗口氧化硅片上进行Si1-xGex外延层的生长.首先分别以不含H2(纯GeH4)和含H2(90% H2稀释的GeH4)的两种Ge源进行选择性外延生长.通过SEM观察两种情况下氧化硅片表面,发现H2的存在对选择性外延生长有至关重要的作用.接着以90% H2稀释的GeH4为Ge源,变化Si源和Ge源的流量比改变H2分压,以获得SiH4和GeH4 (90% H2)的最佳流量比,使外延生长的选择性达到最好. 利用SEM观察在不同流量比时,经40min外延生长后各样品的表面形貌,并对其进行比较,分析了H2分压在Si1-xGex选择性外延生长中的作用机理. 相似文献
20.
We report on the electrical characteristics of the two-dimensional electron gas (2DEG) formed in an InAlAs/InAsxP1-x/InP pseudomorphic composite-channel modulation-doped (MD) structure grown by solid source (arsenic and phosphorus) molecular
beam epitaxy (SSMBE). The As composition, x, of strained InAsxP1-x was determined by x-ray diffraction analysis of InP/InAsxP1-x/InP multi-quantum wells (MQWs) with compositions of x=0.14 to x=0.72. As the As composition increases, the room temperature
sheet resistance of InAlAs/InAsxP1-x/InP composite-channel MD structures grown over a range of As compositions decreased from 510 to 250 Ω/cm2, resulting from the greater 2DEG confinement and lower electron effective mass in the InAsxP1-x channel as x increases. The influence of growth conditions and epitaxial layer designs on the 2DEG mobility and concentration
were investigated using 300 K and 77 K Hall measurements. As the exposure time of the As4 flux on the growth front of InAsxP1-x increased during growth interruptions, the 2DEG mobility, in particular the 77K mobility, was considerably degraded due to
increased roughness at the InAlAs/InAsxP1-x interface. For the InAlAs/InAs0.6P0.4/InP composite-channel MD structure with a spacer thickness of 8 nm, the room temperature 2DEG mobility and density were 7200
cm2/Vs and 2.5 × 1012 cm−2, respectively. These results show the great potential of the InAlAs/InAsxP1-x/InP pseudomorphic composite-channel MD heterostructure for high frequency, power device applications. 相似文献