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1.
Safi Altunöz Hüseyin Çelik Mehmet Cankurtaran 《Central European Journal of Physics》2008,6(3):479-490
The mobility of electrons in vertical transport in GaAs/Ga1−y
Al
y
As barrier structures was investigated using geometric magnetoresistance measurements in the dark. The samples studied had
Ga1−y
Al
y
As (0 ≤ y ≤ 0:26) linearly graded barriers between the n+-GaAs contacts and the Ga0:74Al0:26As central barrier, which contain N
w
(=0, 2, 4, 7 and 10) n-doped GaAs quantum wells. The mobility was determined as functions of (i) temperature (80–290 K) at
low applied voltage (0.01–0.1 V) and (ii) applied voltage (0.005–1.6 V) at selected temperatures in the range 3.5–290 K. The
experimental results for the temperature dependence of low-field mobility suggest that space-charge scattering is dominant
in the samples with N
w
=0 and 2, whereas ionized impurity scattering is dominant in the samples with N
w
=4, 7 and 10. The effect of polar optical phonon scattering on the mobility becomes significant in all barrier structures
at temperatures above about 200 K. The difference between the measured mobility and the calculated total mobility in the samples
with N
w
=4, 7 and 10, observed above 200 K, is attributed to the reflection of electrons from well-barrier interfaces in the quantum
wells and interface roughness scattering. The rapid decrease of mobility with applied voltage at high voltages is explained
by intervalley scattering of hot electrons.
相似文献
2.
V. G. Popov V. G. Krishtop O. N. Makarovskii M. Henini 《Journal of Experimental and Theoretical Physics》2010,111(2):220-224
Resonant tunneling of electrons is thoroughly studied in in-plane magnetic fields. Anticrossing is revealed in a spectrum
of two-dimensional electrons at energies of optical phonons. The magnetic field changes the momentum of tunneling electrons
and causes a voltage shift of a resonance in the tunnel spectra in accordance with the electron dispersion curve. Anticrossing
is clearly observed in second derivative current-voltage characteristics of a resonant tunneling diode made of a double-barrier
Al0.4Ga0.6As/GaAs heterostructure. 相似文献
3.
The heating of electrons in an AlxGa1−x
As/GaAs (x>0.42) heterostructure in a lateral (directed along the heterointerfaces) electric field is studied. Population inversion
on the size-quantization subbands of the Γ valley of GaAs and a giant population inversion between the X-valley states of
AlxGa1−x
As and Γ-valley states of GaAs are predicted. The possibility of using these inversions for achieving stimulated IR emission
is discussed.
Pis’ma Zh. éksp. Teor. Fiz. 68, No. 1, 73–77 (10 July 1998) 相似文献
4.
A combination of the surface diagnostic techniques Auger electron spectroscopy (AES), reflection high energy electron diffraction
(RHEED), and secondary ion mass spectroscopy (SIMS) was used in order to get more detailed information on basic processes
which lead to the formation of high quality monocrystalline GaAs and Al
x
Ga1−x
As films by molecular beam epitaxy (MBE) under ultra-high vacuum conditions. The formation and changes of reconstructed surface
structures on (100) GaAs as a function of growth parameters were observedduring growth by RHEED. AES was used to determine the relative ratio of Ga/As on the surface for different reconstructed structures,
to investigate the impurity contamination on substrate surfaces and grown films, and to study the surface segregation of Sn
in MBE GaAs during doping. Finally, intentional and unintentional impurities incorporated during the growth of GaAs and Al
x
Ga1−x
As by MBE were detected by the SIMS technique immediately after growth within the reaction chamber. 相似文献
5.
《Superlattices and Microstructures》1998,24(4):295-298
We report a design and electroluminescence (EL) investigation of a p-i-n resonant tunneling device based on an Al0.4Ga0.6As/GaAs graded-index waveguide heterostructure. The intrinsic region of the structure consists of a quantum well (QW) surrounded by multiple barrier energy filters providing simultaneous resonant occupation of electron and heavy-hole second excited subbands in the QW. Several peaks are observed in the EL spectra, confirming occupation of the excited subbands. The EL efficiency displays a resonant behavior accompanied by an S-shaped negative differential resistance region in the voltage–current characteristic. Current bistability is demonstrated, leading to bistability in the EL and laser generation spectra. 相似文献
6.
N.K. Cho K.W. Kim J.D. Song W.J. Choi J.I. Lee 《Solid State Communications》2010,150(39-40):1955-1958
A distributed Bragg reflector (DBR) utilizing the digital alloy Al0.9Ga0.1As was grown by using the molecular beam epitaxy (MBE) method for application in 1.3 μm optical communications and compared to the analog-alloy AlGaAs/GaAs DBR. The transmission electron microscopic (TEM) image showed a highly abrupt boundary of AlAs and GaAs, which supports the formation of a digital-alloy Al0.9Ga0.1As layer. The measurement showed that the digital-alloy AlGaAs/GaAs DBR had similar reflection spectra with enhanced uniform distribution over the whole substrate surface compared to the analog-alloy one. In the digital-alloy Al0.9Ga0.1As/GaAs DBR cavity, the reflection dip position was measured at around 1273 nm and the standard deviation of the distribution of the reflection dip was 1.31 nm in wavelength over 1/4 of a three-inch wafer. 相似文献
7.
The current-field characteristics for Al
x
Ga1−x
As alloys under hydrostatic pressure have been calibrated into velocity-field characteristics using low field experimental
data. The saturated drift velocity forx = 0.29 decreases from 7.8 × 106 cm/s atP = 3.5 Kbar to 3.8 × 106 cm/s atP = 8 Kbar. It is shown that the saturated velocity decreases from the value of 1.0 × 107 cm/s in GaAs to about 3.8 × 106 cm/s forx ≈ 0.39. The results should be useful in the design of high field devices of Al
x
Ga1−x
As. 相似文献
8.
L. V. Butov A. V. Mintsev A. I. Filin K. Eberl 《Journal of Experimental and Theoretical Physics》1999,88(5):1036-1044
The kinetics of indirect photoluminescence of GaAs/AlxGa1−x
As double quantum wells, characterized by a random potential with a large amplitude (the linewidth of the indirect photoluminescence
is comparable to the binding energy of an indirect exciton) in magnetic fields B≤12 T at low temperatures T≥1.3 K is investigated. It is found that the indirect-recombination time increases with the magnetic field and decreases with
increasing temperature. It is shown that the kinetics of indirect photoluminescence corresponds to single-exciton recombination
in the presence of a random potential in the plane of the double quantum wells. The variation of the nonradiative recombination
time is discussed in terms of the variation of the transport of indirect excitons to nonradiative recombination centers, and
the variation of the radiative recombination time is discussed in terms of the variation of the population of optically active
excitonic states and the localization radius of indirect excitons. The photoluminescence kinetics of indirect excitons, which
is observed in the studied GaAs/AlxGa1−x
As double quantum wells for which the random potential has a large amplitude, is qualitatively different from the photoluminescence
kinetics of indirect excitons in AlAs/GaAs wells and GaAs/AlxGa1−x
As double quantum wells with a random potential having a small amplitude. The temporal evolution of the photoluminescence
spectra in the direct and indirect regimes is studied. It is shown that the evolution of the photoluminescence spectra corresponds
to excitonic recombination in a random potential.
Zh. éksp. Teor. Fiz. 115, 1890–1905 (May 1999) 相似文献
9.
A. K. Atayan E. M. Kazaryan A. V. Meliksetyan H. A. Sarkisyan 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2010,45(3):126-131
We investigate magnetoexcitonic states in the Ga1−x
1Alx
1As/GaAs/Ga1−x
2Alx
2 As quantum ring with the Winternitz-Smorodinsky confinement potential. A homogeneous magnetic field is directed perpendicularly
to the ring plane. The Coulomb interaction between the electron and hole is assumed as weak and is considered in the framework
of perturbation theory. Obtained results show that the more realistic Winternitz-Smorodinsky confinement potential, which
takes into account a peculiar smoothing of the confinement potential profile, leads to raising of the electron energy levels
as compared to the case of a finite-height rectangular confinement potential. 相似文献
10.
M. Wośko B. Paszkiewicz K. Tarnowski B. Ściana D. Radziewicz W. Salejda R. Paszkiewicz M. Tłaczała 《Opto-Electronics Review》2011,19(4):418-424
The paper presents the application of non-modulation reflectance method for composition profiling of epitaxial AlxGa−xAs/GaAs structures. This non-destructive method is based on spectral measurements and theoretical reflectance spectrum matching.
This is a very accurate and sensitive method of determining the Al composition in AlxGa1−xAs layers and structures with resolution down to 1 nm. In this work, the authors describe theoretic principles of this method
and present experimental results of characterization of different AlGaAs structures to prove the potential of the worked out
method. 相似文献
11.
Summary X-ray double-crystal rocking curves of Ga1−x
Al
x
As/GaAs heterostructures have been calculated using a dynamical diffraction model for the general case of Bragg reflection
geometry. Different experimental configurations have been considered and the possibility of studying both slightly mismatched
and relatively thin layers has been investigated. Experimental rocking curves have been measured using the CuKα
1 radiation, the 004 symmetric reflection and a perfect crystal as the monochromator. An excellent agreement between calculated
and experimental rocking curves has been found and this demonstrates the reliability of both the experimental procedure and
the theoretical approach. 相似文献
12.
高组份Al值的AlxGa1-x As和AlxGa1-x As/GaAs/AlxGa1-xAs/GaAs多层结构的MOCVD生长 总被引:1,自引:1,他引:0
用自制常压MOCVD系统,在半绝缘GaAs衬底上生长高Al组份AlxGa1-xAs(其x值达0.83),和AlxGa1-xAs/GaAs/AlxGa1-xAs/GaAs多层结构,表面镜面光亮。生长层厚度从几十到十几μm可控,测试表明外延层晶格结构完整,x值调节范围宽,非有意掺杂低,高纯GaAs外延层载流子浓度n300K=1.7×1015cm-3,n77K=1.4×1015cm-3,迁移率μ300K=5900cmcm2/V.S,μ77K=55500cm2/V.S。用电子探针,俄歇能谱仪测不出非有意掺杂的杂质,各层间界面清晰平直。 对GaAs,AlGaAs生长层表面缺陷,衬底偏角生长温度及其它生长条件也进行了初步探讨。 相似文献
13.
M. R. Deshpande J. W. Sleight M. A. Reed R. G. Wheeler R. J. Matyi 《Superlattices and Microstructures》1996,20(4):513-522
Zeeman splitting of the ground state of single impurities in the quantum wells of resonant tunneling heterostructures is reported. We determine the absolute magnitude of the effective magnetic spin splitting factorg* for a single impurity in a 44 Å Al0.27Ga0.73As/GaAs/Al0.27Ga0.73As quantum well to be 0.28±0.02. This system also allows for independent measurement of the electron tunneling rates through the two potential barriers and estimation of the occupation probability of the impurity state in the quantum well. 相似文献
14.
O. Yu. Borkovskaya N. L. Dmitruk I. B. Ermolovich R. V. Konakova V. V. Milenin 《Technical Physics》2004,49(3):325-329
The properties of nonrectifying AuGe/GaAs (Al0.4Ga0.6As) contacts exposed to heat treatment, 60Co γ radiation, and γ radiation combined with the application of an electrical bias are studied. A correlation between the
type of interfacial interaction in the contacts and their resistance is found. Results obtained are explained in terms of
a diffusion model with a movable boundary of the metal layer. 相似文献
15.
16.
Optical reflection spectra from a Ga0.7Al0.3As/GaAs heteroboundary are calculated using the approximation of a strongly localized exciton wave function. The calculation
is based on electron Γ6 and hole Γ8
kp-Hamiltonians with position-dependent parameters.
Fiz. Tverd. Tela (St. Petersburg) 40, 872–874 (May 1998) 相似文献
17.
R.Y. Li Z.G. Wang B. Xu P. Jin X. Guo M. Chen 《Applied Physics A: Materials Science & Processing》2007,86(1):19-22
The interface of wet oxidized Al0.97Ga0.03As/GaAs in a distributed Bragg reflector (DBR) structure has been studied by means of transmission electron microscopy and Raman spectroscopy. With the extension of oxidation time, the oxide/GaAs interfaces are not abrupt any more. There is an amorphous film near the oxide/GaAs interface, which is Ga2O3 related to the prolonged heating. In the samples oxidized for 10 and 20 min, there are some fissures along the oxidized AlGaAs/GaAs interfaces. In the samples oxidized or in situ annealed for long time, no such fissures are present due to the complete removal of the volatile products. PACS 68.55.Jk; 68.55.Nq; 68.65.+g; 81.65.Mq 相似文献
18.
Abstract The time-resolved luminescence of an electron-hole plasma in Al0.36Ga0.64As was studied as a function of pressure. Application of hydrostatic pressure varies the energy separation between the conduction band minima at Г and X. The dependence of the intensity ratio of the zero-phonon line and the two phonon replicas on this energy separation shows that scattering from X to Г by alloy disorder is as effective as scattering by phonons. We have further studied the tunneling of electrons between two GaAs quantum wells (QW) of different thicknesses through an Al0.35Ga0.65As barrier. The lifetime of electrons in the narrow QW, which is limitd by electron tunneling into the wider QW, stays constant from 0 to 2.4 GPa, where it drops within 0.1 GPa from 140 ps to less than 7 ps. At this pressure the X-point energy of the barrier coincides with the electron level in the wider QW. We infer that tunneling occurs only via the Г states in the barrier and that X states become effective only when real-state transfer is possible. 相似文献
19.
V. G. Popov Yu. V. Dubrovskiĭ J. -C. Portal 《Journal of Experimental and Theoretical Physics》2006,102(4):677-684
The results of experimental investigation of the vertical electron transport in a GaAs/Al0.3Ga0.7As/GaAs single-barrier tunneling heterostructure with a doped barrier are presented. Two-dimensional accumulation layers appear on different sides of the barrier as a result of the ionization of Si donors in the barrier layer. The nonmonotonic shift of the current peak is found in the I–V curve of the tunneling diode in a magnetic field perpendicular to the planes of two-dimensional layers. Such a behavior is shown to be successfully explained in the model of appearing the Coulomb pseudogap and the pinning of the spin-split Landau levels at the Fermi levels of the contacts. In this explanation, it is necessary to assume that the Landé factor is independent of the filling factors of the Landau levels and is g* = 7.5 for both layers. 相似文献
20.
The Zeeman splitting of the ground states 1s(hh) and 1s(lh) of excitons with heavy and light holes, respectively, in a 15-nm isolated Al0.3Ga0.7As/GaAs quantum well in magnetic fields of up to 20 T is investigated according to the photoluminescence excitation spectra
in the Faraday geometry (σ+− σ− components). The observed anomalous pattern of nonlinear Zeeman splitting and the nonmonotonic behavior of the effective
hole g factor are interpreted in terms of the strong mixing of the magnetoexcitonic states containing light and heavy holes.
Pis'ma Zh. éksp. Teor. Fiz. 64, No. 1, 52–56 (10 July 1996) 相似文献