共查询到10条相似文献,搜索用时 296 毫秒
1.
P. A. Martin J. M. Ballingall P. Ho T. J. Rogers 《Journal of Electronic Materials》1994,23(12):1303-1307
Photoluminescence (PL) has been used for some time the evaluation of pseudomorphic high electron mobility transistor material
structures. Among the results routinely obtained from these structures are estimates of electron sheet density in the InGaAs
channel, either from empirical relationships or from first principles (from direct observation of the Fermi level). We present
a semiempirical line shape model for the study of PL line shapes at low temperatures. We show that the primary source of error
for optical measurement of the sheet density is in the filling of the channel by electrons injected by the incident laser.
We also demonstrate the potential for extraction of structural parameters such as channel composition and thickness from careful
observation of variations in PL transition energies. 相似文献
2.
S. Elhamri W. C. Mitchel W. D. Mitchell R. Berney M. Ahoujja J. C. Roberts P. Rajagopal T. Gehrke E. L. Piner K. J. Linthicum 《Journal of Electronic Materials》2005,34(4):444-449
Resistivity and Hall effect measurements as functions of temperature and magnetic field have been made on AlGaN/GaN heterostructures
grown on silicon substrates. Electronic properties are comparable to those of similar structures grown on sapphire or silicon
carbide. Persistent photocurrent (PPC) effects induced by illumination with blue and ultraviolet (UV) light-emitting diodes
(LEDs) have been investigated. These effects persisted to room temperature. Shubnikov-de Haas (SdH) oscillations were observed
in several samples but only after illumination in some samples. Analysis of the mobility dependence on the carrier density
suggests small angle scattering is responsible for the suppression of the oscillations prior to illumination in those samples. 相似文献
3.
A. Kurtenbach C. Ulrich N. Y. Jin-Phillipp F. Noll K. Eberl K. Syassen F. Phillipp 《Journal of Electronic Materials》1996,25(3):395-400
We report on the growth of InP/GalnP islands on GaAs substrates by solidsource molecular beam epitaxy. It is shown by reflection
high energy electron diffraction and atomic force microscopy that a rapid change from a twodimensional to a three-dimensional
growth mode occurs at about nominally 1.5 monolayers (MLs) InP. Transmission electron microscopy measurements demonstrate
the coherent incorporation of InP islands in an GalnP matrix for nominally 2.5 MLs InP. The energy of the InP photoluminescence
(PL) shifts to lower energies (100 meV) when the growth interruption time between the island and cap layer growth is increased
from 1 to 300 s in case of nominally 3 MLs InP. Simultaneously, an increase of the PL linewidth is observed from 30 to 60
meV. Room temperature photoreflectance measurements on samples with various InP thickness have been performed. Compared to
PL measurements, an additional feature in the photoreflectance spectra is observed for samples with more than 7 MLs InP, which
is attributed to a transition between excited electron and hole states of the islands. 相似文献
4.
A. Kadashchuk A. Andreev H. Sitter N.S. Sariciftci Y. Skryshevski Y. Piryatinski I. Blonsky D. Meissner 《Advanced functional materials》2004,14(10):970-978
We report on photoluminescence (PL) and thermally stimulated luminescence (TSL) in highly ordered nanostructures of para‐sexiphenyl (PSP) grown by hot wall epitaxy (HWE). A low‐energy broad band is observed in the PL spectra that can be attributed to the emission from molecular aggregates. While the intrinsic exciton emission in steady‐state PL dominates at low temperatures, the emission from aggregates increases with elevating temperature and its magnitude depends sensitively on film preparation conditions. Time‐resolved PL measurements showed that the aggregate emission decays with a life‐time of ≈ 4 ns, which is approximately an order of magnitude larger than the lifetime of singlet excitons. TSL data suggests the presence of an energetically disordered distribution of localized states for charge carriers in PSP films, which results from an intrinsic disorder in this material. A low‐temperature TSL peak with the maximum at around 30 K evidences for a weak energy disorder in PSP films, and has been interpreted in terms of a hopping model of TSL in disordered organic materials. 相似文献
5.
The growth of InxGaj1−xAs (x = 0.13–0.25) on GaAs by chemical beam epitaxy (CBE) and laser-modified CBE using trimethylindium (TMIn), triethylgallium
(TEGa), and tris-dimethylaminoarsenic (TDMAAs) has been studied. Reflection high-energy electron diffraction measurements
were used to investigate the growth behavior of InGaAs at different conditions. X-ray rocking curve and lowtemperature photoluminescence
(PL) measurements were used to characterize the InGaAs/GaAs pseudomorphic strained quantum well structures. Good InGaAs/GaAs
interface and optical property were obtained by optimizing the growth condition. As determined by the x-ray simulation, laser
irradiation during the InGaAs quantum well growth was found to enhance the InGaAs growth rate and reduce the indium composition
in the substrate temperature range studied, 440–500°C, where good interfaces can be achieved. These changes, which are believed
to be caused by laser-enhanced decomposition of TEGa and laser-enhanced desorption of TDMAAs, were found to depend on the
laser power density as well. With laser irradiation, lateral variation of PL exciton peaks was observed, and the PL peaks
became narrower. 相似文献
6.
测量了Hg1-xCdxTe光导探测器中电阻率与温度及磁场强度的关系.在Shubnikov-deHaas(SdH)测量中,发现了表面电子的浓度在1.2~55K的范围内没有变化.一个包括体电子和两类表面电子的三带模型被用来分析电阻率随温度变化的关系,由此得到的电学参数与实验及SdH测量获得的结果非常符合 相似文献
7.
M. S. Ramanachalam A. Rohatgi W. B. Carter J. P. Schaffer T. K. Gupta 《Journal of Electronic Materials》1995,24(4):413-419
Photoluminescence (PL) measurements were carried out on commercial ZnO varistor samples that were electrically stressed and/or
annealed at different temperatures. Changes in the intensity of green and yellow luminescence centers were studied as a function
of annealing treatment. It was found that the ZnO luminescence (green and yellow) decrease with increase in annealing temperature,
reach a minimum at 700°C, and increase again beyond 800°C. Furthermore, these green and yellow luminescence bands observed
in the PL spectra are quenched in the ZnO varistor samples, compared to pure ZnO. In an electrically stressed ZnO varistor
sample, the luminescence intensity was found to be higher compared to the as-sintered varistor sample. Annealing of the stressed
varistor sample resulted in a decrease of the luminescence intensity. These PL observations are consistent with previous deep
level transient spectroscopy and doppler positron annihilation spectroscopy results. All of the experimental results are consistent
with the ion migration model of degradation and can be explained using a grain boundary defect model. 相似文献
8.
N. C. Giles Jaesun Lee T. H. Myers Zhonghai Yu B. K. Wagner R. G. Benz C. J. Summers 《Journal of Electronic Materials》1995,24(5):691-696
A comprehensive study of the properties of undoped and iodine-doped CdTe structures by photoluminescence (PL) and photoreflectance
(PR) is reported. Undoped bulk CdTe and iodine-doped CdTe layers grown by metalorganic molecular beam epitaxy on (lOO)-oriented
CdTe and (211)B-oriented GaAs substrates with electron concentrations ranging from 1014 to mid-1018 cm-3 were included in this study. Lineshape modeling of 80KPL and PR spectra indicated the presence of both free exciton and donor-hole
transitions at the higher doping levels. Strong PL and PR signals were also observed at room temperature. If only a single
transition is considered for the analysis of the 300K spectra, the PL emission peak and the PR transition energy both exhibit
a strong dependence on electron concentration for doped layers. However, lineshape modeling of the room-temperature spectra
indicated the presence of multiple transitions consisting of free exciton and direct band-to-band transitions. The use of
two transitions resulted in a constant value of bandgap over the entire range of conductivities studied. A strong correlation
remained between the broadening of the PR and PL spectra and excess carrier concentration ND-NA. In addition, the E1 transition energy measured by PR was found to vary dramatically with growth conditions. 相似文献
9.
用光的反射光谱和光的光致发光光谱的测量对Ga0.69In0.31NxAs1-x/GaAs 的单量子阱的光学特性作了研究,在单量子阱的反射光谱中,观察到 GaAs 能隙之上的 Franz-Keldysh 振荡和来源于量子阱区的各种类激子跃迁,Franz-Keldysh 振荡确定量子阱的内建电场并发现它是随 N 的浓度增加而增加;反射信号随样品中氮耦合增强而减弱,因为温度降低时载流子的定域作用导致调制效应的弱化.激子跃迁的能量和温度关系按照 Varshni 和爱因斯坦一玻司方程作了研究,在 PL 谱中观察到的 11H 跃迁能量和谱线展宽的温度反常关系解释为起源于氮耦合所引起的定域态,这种样品的谱线特征为随氮成份增加出现红移,氮结合作用的另一个结果是晶体的性质严重退化,明显地表现线宽受温度的影响增大.总之,氮引进系统会观察到GaAs 边带以上的 FkO 导致内建场增大,有低温时高激发态叠加并屏闭在定域态上的部分调制外场作用的倾向.PL 峰能量和线宽对温度的反常关系可以理解为由氮的结合作用引起的形成定域态和去除定域态的竞争结果. 相似文献
10.
A novel insulated gate technology for InGaAs high electron mobility transistors (HEMT) is described. It utilizes a silicon
interface control layer (Si ICL)-based passivation structure. By applying an HF surface treatment, the technology becomes
applicable to the air-exposed surfaces of InGaAs and InAlAs. The basic metal-insulator-semiconductor structures were fabricated
and characterized in detail by x-ray photoelectron spectroscopy analysis and capacitance-voltage measurements. The interface
has been shown to be essentially free from interface states. InGaAs insulated gate HEMTs (IGHEMT) were then success-fully
fabricated. The fabricated recessed gate IGHEMTs have good gate control of the drain current with good pinch-off characteristics.
A highest effective mobility of 2010 cm2/Vs was obtained. The devices show extremely low gate leakage currents below lnA/mm. 相似文献