共查询到20条相似文献,搜索用时 31 毫秒
1.
E. V. Kiselyova M. A. Kitaev S. V. Obolensky V. T. Trofimov V. A. Kozlov 《Technical Physics》2005,50(4):528-530
The radiation resistance of GaAs MESFETs with a channel length of 30–80 nm is studied. It is shown that the resistance is
controlled by quasi-ballistic effects in the transistor channel and amounts to 5 × 1014 −5 × 1015 fast neutrons per square centimeter. 相似文献
2.
J.L. Pan J.E. McManis M. Gupta M.P. Young J.M. Woodall 《Applied Physics A: Materials Science & Processing》2008,90(1):105-112
Materials exhibiting strong optical emission also exhibit strong absorption at the same wavelengths because both emission
and absorption are governed by the same optical dipole and density-of-states. Laser action requires a carrier injection large
enough for emission to exceed absorption at laser wavelengths. Thus, strong self-absorption at luminescent wavelengths raises
the operating current of LEDs, lasers, and optical amplifiers. Here we demonstrate that, contrary to conventional expectations,
materials designed with novel deep centers achieve surprisingly large optical emission while, simultaneously, the inverse
process of optical absorption remains very small. A striking consequence is that materials designed with our novel deep centers
achieve transparency at a carrier injection which is four-orders-of-magnitude lower than in all technologically important
semiconductors. Simultaneously, and surprisingly, our novel deep centers in GaAs achieve an optical gain, Einstein B coefficient,
and radiative efficiency significantly larger than in direct-band-gap materials at 1.3–1.5 μm. We engineered this dramatic
reduction of the injection to achieve transparency while retaining strong optical emission in our novel material by making
use of a Franck–Condon shift of absorption away from luminescent wavelengths.
PACS 71.55.Eq; 71.55.-i; 78.67.-n; 81.10.-h; 85.60.Jb 相似文献
3.
V. A. Volodin M. D. Efremov V. Ya. Prints V. V. Preobrazhenskii B. R. Semyagin 《JETP Letters》1996,63(12):994-999
The localization of longitudinal optical phonons in GaAs/AlAs lateral superlattices and quantum wires grown on faceted GaAs
(311)A surfaces are investigated by means of Raman scattering spectroscopy. The frequencies of the localized phonons are found
to decrease as the average thickness of the GaAs layer is decreased from 21 to 15 Å. As the GaAs thickness is decreased further
to 11.3 and 8.5 Å, the frequencies of the localized phonons increases sharply in connection with the formation of an array
of quantum wires. The frequencies calculated in a two-dimensional chain model agree with the experimental values. This makes
it possible to interpret the increase in the frequencies of localized phonon states as being the result of the quantization
of phonons in the array of one-dimensional objects. The results obtained support the model of GaAs (311)A surface faceting
with a facet height of 10.2 Å.
Pis’ma Zh. éksp. Teor. Fiz. 63, No. 12, 942–946 (25 June 1996) 相似文献
4.
É. A. Il’ichev 《Technical Physics》1998,43(5):611-613
An original nondestructive method for the local deep-level diagnostics of semi-insulating materials is discussed. The method,
called deep-level relaxation optoelectronic spectroscopy (DLROS), is based on the contactless recording of relaxation processes
of the electron-hole and trap systems. It can be used to determine the type, energy, and capture cross section of deep energy
centers and to establish their distribution in a wafer for integrated-circuit applications. The DLROS method is effective
for the production input, interim (between operations), and output monitoring of substrates and GaAs structures. Unlike DLTS,
it does not require the fabrication of measurement electrodes on samples.
Zh. Tekh. Fiz. 68, 141–143 (May 1998) 相似文献
5.
G. Sai Saravanan K. Mahadeva Bhat H. P. Vyas K. Muraleedharan A. P. Pathak 《辐射效应与固体损伤》2013,168(9):737-748
The active layers of Metal Semiconductor Field Effect Transistors (MESFETs) are obtained by Si29+ ion implantation in GaAs. Implantation was done at 35 keV with a higher dose near the wafer surface for facilitating easier formation of ohmic contacts, and at 180 keV with a lower dose for obtaining the device channel. Post-implantation annealing was carried out in a rapid thermal processor for activating the implants. Very high activation levels of about 60% for the n+ GaAs layer, and 85% for the n-GaAs channel layer were achieved by annealing at 955 °C for 25 s. Activation was characterized using C–V profiling, secondary ion mass spectrometry and by electrical device data of fabricated MESFETs. We attempt an experimental correlation between the ohmic contact resistance (R c) and activation of both the n+ and the channel layer. It was found that very high and simultaneous activation of the n+ and channel layers results in very low contact resistances. The conduction of source-drain current into the channel is easily facilitated due to reduction in the resistance of the transition region at the interface of n+-contact and n-channel layers. 相似文献
6.
A technique that makes it possible to investigate the mechanisms of phase relaxation of excitons in GaAs single quantum wells
has been developed using resonant reflection spectroscopy. The dependence of the oscillator strength of the exciton transition
on the quantum well thickness has been measured in the thickness range 9.1–30.0 nm. It has been demonstrated that the oscillator
strength with a high accuracy does not depend on the temperature in the range 8–90 K. The temperature dependence of the homogeneous
broadening has been measured, and the inhomogeneous broadening of the resonance exciton line has been determined. A nonmonotonic
dependence of the spectral broadening of the exciton line on the intensity of the resonant excitation at a temperature of
8 K has been revealed for the sample with a high-quality quantum well. It has been established that an increase in the excitation
level by five orders of magnitude above the linear limit leads to an insignificant change in the oscillator strength of the
exciton transition and to a multiple broadening of the spectral line profile. 相似文献
7.
The densities of electrons in the two-dimensional and doped channels of selectively doped AlGaAs/GaAs heterostructures are
calculated. It is shown that traps and surface states in the AlGaAs layer can change the sign of the temperature dependence
of the electron density in the two-dimensional channel.
Zh. Tekh. Fiz. 68, 140–142 (October 1998) 相似文献
8.
Improved performance of 4H-SiC metal-semiconductor field-effect transistors with step p-buffer layer
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An improved 4H-SiC metal-semiconductor field-effect transistors (MESFETs) with step p-buffer layer is proposed, and the static and dynamic electrical performances are analysed in this paper. A step p-buffer layer has been applied not only to increase the channel current, but also to improve the transconductance. This is due to the fact that the variation in p-buffer layer depth leads to the decrease in parasitic series resistance resulting from the change in the active channel thickness and modulation in the electric field distribution inside the channel. Detailed numerical simulations demonstrate that the saturation drain current and the maximum theoretical output power density of the proposed structure are about 30% and 37% larger than those of the conventional structure. The cut-off frequency and the maximum oscillation frequency of the proposed MESFETs are 14.5 and 62 GHz, respectively, which are higher than that of the conventional structure. Therefore, the 4H-SiC MESFETs with step p-buffer layer have superior direct-current and radio-frequency performances compared to the similar devices based on the conventional structure. 相似文献
9.
用DLTS技术结合光电容定态谱、瞬态谱、OITS谱研究了GaAs0.6P0.4:Te深中心的光电性质和电声耦合作用,在GaAs0.6P0.4:Te中检测到两种深中心(A和B中心),表观热激活能分别为0.20和0.40eV,光离化阀值分别为0.60和1.31eV。详细研究了B中心的特性,测量了光离化截面谱的温度关系,发现有明显的声于展宽现象和晶格弛豫效应,并在低温(90K)观察到B中心的持续光电导效应。描绘出位形坐标图,说明了实验结果,较好地描述了B中心的特性,确认B中心属于DX中心。 相似文献
10.
The energy dependencies of the transmission coefficients of electrons in GaAs/AlAs-structures with a different number of layers
are obtained using the three-valley model developed earlier. It is shown that it is important to take into account the ΓX-mixing
with GaAs/AlAs(001)-heterointerfaces in the electron wave functions for such structures. A relation is established between
the form of the Γ- and X-resonances in the transmission spectrum, the thickness of the layers and their number. Some features
in the behavior of the resonances are analyzed using the simple two-valley model. It is shown that to study ΓX-mixing, structures
which include at least one electrode of AlAs are preferable.
V. D. Kuznetsov Siberian Physico-Technical Institute, Tomsk State University. Translated from Izvestiya Vysshikh Uchebnykh
Zavedenii, Fizika, No. 1, pp. 63–69, January, 1997. 相似文献
11.
We show that when polystyrene is exposed (for 15–60 sec) to a UV laser light beam (λ = 248 nm), its absorption and luminescent
properties change significantly. In the irradiated polymer, optical centers are formed with absorption bands in the 280–460
nm region and fluorescence bands in the 330–520 nm region. We have established the chemical structure of the optical centers
for fluorescence of polystyrene.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 1, pp. 54–58, January–February, 2006. 相似文献
12.
V. A. Kul’bachinskii V. G. Kytin R. A. Lunin A. V. Golikov A. V. Demin A. S. Bugaev A. P. Senichkin A. De Visser R. T. F. Van Schaijk 《Journal of Experimental and Theoretical Physics》1999,89(6):1154-1159
The effect of illumination with various wavelengths λ (770 nm<λ<1120 nm) on the conductivity of GaAs structures with tin δ-doping of the vicinal faces was investigated in the temperature range 4.2–300 K. Negative persistent photoconductivity was
found in strongly doped samples. It was shown on the basis of the results of investigations of the Hall and Shubnikov-de Haas
effects that the negative photoconductivity is due to a large decrease in the electron mobility with increasing electron density.
The decrease of electron mobility is explained by ionization of DX centers, which destroys the spatial correlation in the
distribution of positively charged donors and negatively charged DX centers.
Zh. éksp. Teor. Fiz. 116, 2130–2139 (December 1999) 相似文献
13.
L. A. Lisitsyna 《Russian Physics Journal》1996,39(11):1050-1066
The processes of creating and transforming electronic color centers in an LiF crystal irradiated with a nanosecond electron
pulse are investigated using pulse spectrometry with nanosecond resolution for times in the range 10−8 to 105 sec. It is shown that the thermally activated mechanism of forming Frenkel pairs in the 12–200 K range consists of successively
creating exciton states, as the temperature rises, having different degrees of spatial separation of the electron and hole
components. It is concluded that the structure of self-trapped excitons evolves as a function of temperature and time, and
that this evolution commences for any alkali halide crystal with the creation of self-trapped excitons ofD
2h point symmetry at 4 K. It is established that the interaction of electronic excitations with electronic color centers changes
the properties of both the electronic excitations themselves and the color centers. In a crystal containing neutral electronic
centers there is a fall in the yield of self-trapped excitons and Frenkel pairs and an increase in the contribution of the
radiative channel for loss of the irradiation energy by the color centers. A mechanism is proposed for exciting luminescence
of electronic color centers. It is established that short-lived irradiation-induced states exist, in particular a change in
the spin state or in just the energy state of a center in the irradiation field, and that the appearance of these states changes
the efficiency and directivity of the charge evolution of the electronic color centers.
State Architectural Building Academy, Tomsk. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 57–75,
November, 1996. 相似文献
14.
Yu. P. Rakovich A. L. Gurskii A. S. Smal’ A. A. Gladyshchuk Kh. Khamadi G. P. Yablonskii M. Khoiken 《Physics of the Solid State》1998,40(5):812-813
The exciton reflectance and photoluminescence spectra of epitaxial ZnSe/GaAs layers with a thickness of 2–4 μm are investigated
in the temperature range 10–120 K. It is shown that one of the causes of the formation of the doublet structure of the A
n=1 photoluminescence band is interference of the exciton radiation at the boundaries of the near-surface dead layer.
Fiz. Tverd. Tela (St. Petersburg) 40, 881–883 (May 1998) 相似文献
15.
Model and analysis of drain induced barrier lowering effect for 4H--SiC metal semiconductor field effect transistor
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Based on an analytical solution of the two-dimensional Poisson
equation in the subthreshold region, this paper investigates the
behavior of DIBL (drain induced barrier lowering) effect for short
channel 4H--SiC metal semiconductor field effect transistors
(MESFETs). An accurate analytical model of threshold voltage shift
for the asymmetric short channel 4H--SiC MESFET is presented and
thus verified. According to the presented model, it analyses the
threshold voltage for short channel device on the L/a (channel
length/channel depth) ratio, drain applied voltage VDS and
channel doping concentration ND, thus providing a good basis
for the design and modelling of short channel 4H--SiC MESFETs device. 相似文献
16.
Many studies have been done on low energy (1–200 keV) and high dose (1016–1017) implantation of Mn in GaAs. This study is an attempt to incorporate Mn ions in GaAs through implantation of 1 MeV Mn+1 ions in semi-insulating GaAs substrates at doses of 3×1015/cm2 and subsequent annealing. This was done to find out if any alloy of Mn–Ga–As, or binary compounds of Mn–Ga or Mn–As form
due to annealing of Mn+1 ions implanted in GaAs substrates. High Resolution XRD (HRXRD) performed before annealing shows a possibility of Ga–Mn–As
alloy formation, and after annealing at 800°C, except for GaAs main peaks no other phase peaks were detected. Scanning electron
microscopy (SEM) shows nanostructures of various dimensions which are thought to be formed due to the defects generated due
to implantation. Fourier Transform Infrared (FTIR) study shows the shift in bandgap due to Mn doping. Raman spectroscopy shows
the red shift in LO and TO peak positions of GaAs after annealing, which indicates the presence of disorder and damage due
to implantation. Resistivity measurement shows a thermally activated semiconductor character of charge conduction with an
activation energy of 51 meV and this activation may have occurred through the transitions from impurity band to valence band.
Large positive (∼25%) magnetoresistance and a mixture of ferromagnetic and paramagnetic behavior obtained in the magnetization
measurement indicate the presence of ferromagnetic MnAs nanoclusters embedded in paramagnetic GaAs:Mn matrix. 相似文献
17.
The optical absorption of GaAs crystals with thicknesses d=0.4−4.4 μm is measured in the exciton-polariton resonance region at a temperature of 1.7 K. As the thickness is reduced,
both a broadening of the exciton line and increased absorption with a negligible Stark shift are observed. The way the absorption
spectra vary with crystal thickness is examined in terms of a competition between two regions for light-exciton interactions
in the crystal: in the field of surface charges and electric-field free.
Fiz. Tverd. Tela (St. Petersburg) 40, 869–871 (May 1998) 相似文献
18.
V. Ya. Demikhovskii A. V. Telezhnikov 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2010,4(3):423-431
The electron energy spectrum and wave functions for a quasi-one-dimensional channel with Rashba spin-orbit coupling are calculated.
The dynamics of wave packets in thin wires based on GaAs/In0.23Ga0.77As and AlGaAs/GaAs heterostructures with Rashba spin-orbit coupling are studied. Spin polarizations are found. The effect
of splitting of wave packets with respect to their centers of mass and Zitterbewegung of their centers are discovered. The
characteristics of wave-packet oscillations and spin density for free electrons and under confinement conditions are compared.
A method for controlling the conductance of the quasi-one-dimensional channel using a controlling electrode is proposed. 相似文献
19.
A study is reported of the optical properties of wide-gap, predominantly ionic cadmium fluoride crystals in photo-and thermally
stimulated transformations of metastable indium and gallium centers. An analysis of these properties leads one to a conclusion
of gallium having two metastable states (two types of deep centers). The deep-center binding energies and the barriers separating
the shallow (hydrogenic) and deep centers have been determined for both impurities. Configuration-coordinate diagrams are
developed, and microscopic models for the deep centers are proposed. It is concluded that these centers are identical with
the metastable DX centers in typical semiconducting crystals. Thus cadmium fluoride is the most ionic among the crystals where DX centers have thus far been found. The potential of using such crystals for optical information recording is discussed.
Fiz. Tverd. Tela (St. Petersburg) 39, 2130–2136 (December 1997) 相似文献
20.
E. M. Shishonok 《Journal of Applied Spectroscopy》2007,74(2):272-277
Complex and multiband photoluminescence spectra for GB and HBN centers in single crystals of cubic boron nitride (cBN) were
recorded in the wavelength ranges 385–400 nm and 365–395 nm and the nature of these centers was studied. The use of models
involving resonance vibrations and strongly shifted configuration diagrams for the electronic ground state and excited state
made it possible to associate formation of the GB-1 center with the presence of tungsten impurity in cBN. It was established
that the HBN band in the 300–350 nm range of the cathodoluminescence spectra of cBN polycrystals, single crystals, and micropowders
is associated with luminescence centers present in microinclusions of graphite-like boron nitride (hBN). The nature of the
hBN band is tentatively interpreted within the model of recombination of donor and acceptor defects in hBN: respectively nitrogen
vacancies and carbon atoms in positions substituting for nitrogen.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 2, pp. 241–246, March–April, 2007. 相似文献