共查询到20条相似文献,搜索用时 15 毫秒
1.
A. S. Shkolnik A. V. Savelyev L. Ya. Karachinsky N. Yu. Gordeev R. P. Seisyan G. G. Zegrya S. Pellegrini G. S. Buller V. P. Evtikhiev 《Semiconductors》2008,42(3):291-297
The results of time-resolved photoluminescence studies of heterostructures containing monolayer arrays of InAs/GaAs quantum dots are presented. A two-component time dependence of intensity of photoluminescence from the ground state of quantum dots, with characteristic times of the slow component up to hundreds of nanoseconds and those of rapid one several nanoseconds, is studied. It is shown that the slow component is determined by the transport of nonequilibrium charge carriers between the quantum dots. At low temperatures, the time of the slow component is determined by tunneling, and at high temperatures by thermal escape of nonequilibrium charge carriers. The ratio of the contributions of tunneling and thermal escape is determined by the degree of isolation of quantum dots. A theoretical model is constructed that describes the effect of the dynamics of carrier transport on the emergence and decay of the slow component of photoluminescence. 相似文献
2.
V. G. Talalaev B. V. Novikov S. Yu. Verbin A. B. Novikov Dinh Son Thath I. V. Shchur G. Gobsch R. Goldhahn N. Stein A. Golombek G. É. Tsyrlin V. N. Petrov V. M. Ustinov A. E. Zhukov A. Yu. Egorov 《Semiconductors》2000,34(4):453-461
Photoluminescence (PL) spectra of InAs/GaAs heteroepitaxial structures with quantum dots (QDs) have been studied. The structures were grown by submonolayer migration-enhanced epitaxy on vicinal substrates with the amount of deposited InAs close to the critical value of 1.8 monolayer (ML). The origin and evolution of the structure of PL spectra were studied in relation to the direction and angle of misorientation, temperature, and power density and spectrum of the exciting radiation. A blue shift and narrowing of the PL band with increasing misorientation angle was established experimentally. The fact that QDs become smaller and more uniform in size is explained in terms of a lateral confinement of QDs on terraces with account taken of the step bunching effect. The temperature dependences of the positions and full widths at half-maximum (FWHM) of PL bands are fundamentally different for isolated and associated QDs. The exciton ground states contribute to all low-temperature spectral components. The excited exciton state contributes to the recombination emission from QDs, as evidenced by the temperature dependence of the integrated intensity of the PL bands. A quantitative estimate is given of the electronic structure of different families of InAs QDs grown on GaAs substrates misoriented by 7° in the [001] direction. 相似文献
3.
In this paper, we present the growth and photoluminescence (PL) results of InAs quantum dots (QDs) on a p-type porous GaAs (001) substrate. It has been shown that critical layer thickness of InAs overgrowth on porous GaAs has been enhanced compared to that deposited on nominal GaAs. Using porous GaAs substrate, growth interruption and depositing 10 atomic monolayer (ML) In0.4Ga0.6As on InAs QDs, photoluminescence measured at 10 K exhibits an emission at 0.739 eV (∼1.67 μm) with an ultranarrow full width at half maximum (FWHM) of 16 meV. This emission represents the longer wavelength obtained up to date to our knowledge and has been attributed to the radiative transition in the InAs QDs. 相似文献
4.
P.O. Holtz E.S. Moskalenko M. Larsson K.F. Karlsson W.V. Schoenfeld P.M. Petroff 《Microelectronics Journal》2008,39(3-4):331-334
A low-temperature micro-photoluminescence (μ-PL) investigation of InAs/GaAs quantum dots (QDs) exposed to a lateral external electric field is reported. It is demonstrated that the QDs PL signal could be increased several times by altering the external and/or the internal electric field. The internal field in the vicinity of the dots could be altered by means of an additional infra-red laser. We propose a model, which is based on an essentially faster lateral transport of the charge carriers achieved in an external electric field. Consequently, also the capture probability into the dots and subsequently the dot luminescence is also enhanced. The results obtained suggest that the lateral electric fields play a major role for the dot luminescence intensity measured in our experiment. 相似文献
5.
A theoretical model for calculating the energy characteristics of surfaces of InAs quantum dots in a GaAs(100) matrix is described. The model is based on notions of nonequilibrium thermodynamics and surface physics. The results of calculating the magnitudes of the surface energy and adhesion physical quantities as well as pressures in the vicinity of the edges of InAs quantum dots in a GaAs(100) matrix are presented. The causes of bending of the profile of the lower part of the quantum dot are presented using the Young relationship. These results can be used to asses the stress-relaxation mechanisms during the course of the selforganization of InAs quantum dots in a GaAs(100) matrix. 相似文献
6.
A. F. Tsatsul’nikov B. V. Volovik N. N. Ledentsov M. V. Maksimov A. Yu. Egorov A. E. Zhukov A. R. Kovsh V. M. Ustinov Chao Chen P. S. Kop’ev Zh. I. Alfërov V. N. Petrov G. É. Tsirlin D. Bimberg 《Semiconductors》1998,32(1):84-89
The formation of InAs quantum dots grown by submonolayer migration-enhanced molecular-beam epitaxy on GaAs(100) surfaces with
various misorientation angles and directions is investigated. It is shown for the deposition of 2 monolayers (ML) of InAs
that increasing the misorientation angle above 3° along the [010],
, and [011] directions leads to the formation of several groups of quantum dots differing in geometric dimensions and electronic
structure.
Fiz. Tekh. Poluprovodn. 32, 95–100 (January 1998) 相似文献
7.
在该研究中,通过激光全息和湿法腐蚀的方法在InAs/GaAs量子点材料上制备光子晶体,研究了由激光二极管激发制备了光子晶体的InAs / GaAs量子点材料的光致发光光谱.发现具有光子晶体的量子点材料的光谱显示出多峰结构,光子晶体对短波长部分的发光增强和调制比对长波长部分的增强和调制更明显.InAs / GaAs量子点的光致发光光谱通过刻蚀形成的光子晶体结构得到了调控,并且量子点的激发态发光得到了明显增强. 相似文献
8.
M. M. Sobolev A. R. Kovsh V. M. Ustinov A. Y. Egorov A. E. Zhukov 《Journal of Electronic Materials》1999,28(5):491-495
In the present work, we report on the investigation of a p-n heterostructure with InAs/GaAs quantum dots (QD) by capacitance-voltage
and deep level transient spectroscopy. We have observed controllable and reversible metastable population of the energy states
of quantum dots and interface in the structure containing one plane of InAs QDs as a function of temperature of isochronous
annealing as well as under bias-on-bias-off cooling conditions and white light illumination. This effect was attributed to
the change in the Fermi level position due to the hole capture on self-trapped defects similar to the DX center in GaAs after
isochronous annealing and white light illumination. 相似文献
9.
A report is presented on the observation of hole excitations in unintentionally p-doped self-assembled InAs/GaAs quantum dots by resonant Raman spectroscopy. The small difference in the valence intraband energy values obtained by Raman and PL spectra is explained by the Coulomb interaction between electrons and holes. However, the reason why the maximum resonance occurs at a slightly higher energy than that of the hole excitation seen in Raman spectra is unknown. 相似文献
10.
ZHANG Xiao-song DONG Xiao-yi LIU Yan-ge KAI Gui-yun WANG Zhi LI Lan HAN Xu LI Yan 《光电子快报》2007,3(5):337-338
PbS quantum dots were prepared in the aqueous medium from readily available precursors. The shape of the particles isapproximately spherical, and the average particle size observed from HRTEM image was 7-8 nm. We applied PbS quantumdots and PMMA polymer to fabricate PbS quantum dots-PMMA composites, and investigate the photoluminescence PbSquantum dots in PMMA matrix with different mass ratio. PbS quantum dots in PMMA matrix have broad emission be-tween 900 nm and 1 500 nm and photoluminescence peak at 1 179 nm. Additionally, the photoluminescence intensityincreases with increasing the dopant concentration. PbS quantum dots-PMMA polymer composites can be potentially usedfor polymer optical fiber and electroluminescence (EL) in optical communication. 相似文献
11.
S. Rouvimov Z. Liliental-Weber W. Swider J. Washburn E. R. Weber A. Sasaki A. Wakahara Y. Furkawa T. Abe S. Noda 《Journal of Electronic Materials》1998,27(5):427-432
Vertical ordering in stacked layers of InAs/GaAs quantum dots is currently the focus of scientific research because of its
potential for optoelectronics applications. Transmission electron microscopy was applied to study InAs/GaAs stacked layers
grown by molecular-beam-epitaxy with various thicknesses of GaAs spacer. Thickness dependencies of quantum dot size and their
ordering were observed experimentally and, then, compared with the results of strain calculations based on the finite element
method. The vertical ordering did occur when the thickness of the GaAs spacer was comparable with the dot height. The ordering
was found to be associated with relatively large InAs dots on the first layer. Quantum dots tend to become larger in size
and more regular in plane with increasing numbers of stacks. Our results suggest that the vertical ordering is not only affected
by strain from the InAs dots on the lower layer, but by total strain configuration in the multi-stacked structure. 相似文献
12.
G. V. Astakhov V. P. Kochereshko D. G. Vasil’ev V. P. Evtikhiev V. E. Tokranov I. V. Kudryashov G. V. Mikhailov 《Semiconductors》1999,33(9):988-990
The photoluminescence spectra in an external magnetic field of an ensemble of InAs quantum dots grown by molecular beam epitaxy
on a (001) GaAs substrate with a disorientation in the [010] direction are studied. A redistribution of the photoexcited carriers
among different groups of dots under the influence of the magnetic field is observed. The concentration of quantum dots is
determined by analyzing the data.
Fiz. Tekh. Poluprovodn. 33, 1084–1087 (September 1999) 相似文献
13.
B. N. Zvonkov I. G. Malkina E. R. Lin’kova V. Ya. Aleshkin I. A. Karpovich D. O. Filatov 《Semiconductors》1997,31(9):941-946
The capacitive photovoltage and photoconductivity spectra of GaAs/InAs heterostructures with quantum dots is discussed. For
these structures, which were fabricated by metallorganic gas-phase epitaxy, the photosensitivity spectrum has a sawtoothed
shape in the wavelength range where absorption by the quantum dots takes place, which is characteristic of a δ-function-like density of states function. The spectra also exhibit photosensitivity bands associated with the formation of
single-layer InAs quantum wells in the structure. An expression is obtained for the absorption coefficient of an ensemble
of quantum dots with a prespecified size distribution. It is shown that the energy distribution of the joint density of states,
the surface density of quantum dots, and the effective cross section for trapping a photon can all be determined by analyzing
the photosensitivity spectrum based on this assumption.
Fiz. Tekh. Poluprovodn. 31, 1100–1105 (September 1997) 相似文献
14.
S. Chakrabarti S. Fathpour K. Moazzami J. Phillips Y. Lei N. Browning P. Bhattacharya 《Journal of Electronic Materials》2004,33(4):L5-L8
The effect of pulsed laser annealing (PLA), using an excimer laser, on the luminescence efficiency of self-organized InAs/GaAs
and In0.4Ga0.6As/GaAs quantum dots has been investigated. It is found that such annealing can enhance both the peak and integrated photoluminescence
(PL) efficiency of the dots, up to a factor of 5–10 compared to as-grown samples, without any spectral shift of the luminescence
spectrum. The improved luminescence is attributed to the annealing of nonradiative point and extended defects in and around
the dots. 相似文献
15.
Ya. V. Terent’ev O. G. Lyublinskaya A. A. Toropov B. Ya. Meltser A. N. Semenov V. A. Solov’ev S. V. Ivanov 《Semiconductors》2009,43(5):635-639
Magnetooptical studies of heterostructures with type-II InSb quantum dots in the InAs matrix grown by molecular beam epitaxy are carried out. Unusual behavior of magnetophotoluminescence from quantum dots measured in the Faraday geometry in the samples with multiple planes of quantum dots is found. Specifically, the peak with σ? polarization, which corresponds to transitions of electrons with s = +1/2, has a higher energy than the σ+ peak corresponding to s = ?1/2, which contradicts the negative value of the electron g factor both in the InAs matrix and in the InSb quantum dot. The effect can be interpreted as the result of competition of two channels of radiative recombination, which differ by the initial states of electrons belonging either to the InSb quantum dots or to shallow-level donors in the InAs matrix. 相似文献
16.
Electron and hole emission from states of a ten-layer system of tunneling-coupled vertically correlated InAs/GaAs quantum
dots (QDs) is studied experimentally by capacitance—voltage measurements and deep-level transient spectroscopy. The thickness
of GaAs interlayers separating sheets of InAs QDs was ≈3 nm, as determined from transmission electron microscope images. It
is found that the periodic multimo-dal DLTS spectrum of this structure exhibits a pronounced linear shift as the reverse-bias
voltage U
r applied to the structure is varied. The observed behavior is a manifestation of the Wannier—Stark effect in the InAs/GaAs
superlattice, where the presence of an external electric field leads to the suppression of coupling between the wave functions
of electron states forming the miniband and to the appearance of a series of discrete levels called Wannier—Stark ladder states. 相似文献
17.
Dandan Ning Yanan Chen Xinkun Li Dechun Liang Shufang Ma Peng Jin Zhanguo Wang 《半导体学报》2020,41(12):122101-122101-6
Photoluminescence (PL) test was conducted to investigate the effect of rapid thermal annealing (RTA) on the optical performance of self-assembled InAs/GaAs quantum dots (QDs) at the temperatures of 16 and 300 K. It was found that after RTA treatment, the PL spectrum of the QDs sample had a large blue-shift and significantly broadened at 300 K. Compared with the as-grown InAs QDs sample, the PL spectral width has increased by 44.68 meV in the InAs QDs sample RTA-treated at 800 °C. The excitation power-dependent PL measurements showed that the broadening of the PL peaks of the RTA-treated InAs QDs should be related to the emission of the ground state (GS) of different-sized InAs QDs, the InAs wetting layer (WL) and the In0.15Ga0.85As strain reduction layer (SRL) in the epitaxial InAs/GaAs layers. 相似文献
18.
This paper presents the temperature dependence measurements characterisation of several InAs/GaAs quantum dots (QDs) solar cell devices. The devices with cylindrical geometry were fabricated and characterised on-wafer under 20 suns in a temperature range from 300°K to 430°K. The temperature dependence parameters such as open circuit voltage, short circuit density current, fill factor and efficiency are studied in detail. The increase of temperature produces an enhancement of the short circuit current. However, the open circuit voltage is degraded because the temperature increases the recombination phenomena involved, as well as reducing the effective band gap of the semiconductor. 相似文献
19.
V. N. Nevedomskii N. A. Bert V. V. Chaldyshev V. V. Preobrazhenskii M. A. Putyato B. R. Semyagin 《Semiconductors》2011,45(12):1580-1582
An electron-microscopy study of GaAs structures, grown by molecular-beam epitaxy, containing two coupled layers of InAs semiconductor
quantum dots (QDs) overgrown with a thin buffer GaAs layer and a layer of low-temperature-grown gallium arsenide has been
performed. In subsequent annealing, an array of As nanoinclusions (metallic QDs) was formed in the low-temperature-grown GaAs
layer. The variation in the microstructure of the samples during temperature and annealing conditions was examined. It was
found that, at comparatively low annealing temperatures (400–500°C), the formation of the As metallic QDs array weakly depends
on whether InAs semiconductor QDs are present in the preceding layers or not. In this case, the As metallic QDs have a characteristic
size of about 2–3 nm upon annealing at 400°C and 4–5 nm upon annealing at 500°C for 15 min. Annealing at 600°C for 15 min
in the growth setup leads to a coarsening of the As metallic QDs to 8–9 nm and to the formation of groups of such QDs in the
area of the low-temperature-grown GaAs which is directly adjacent to the buffer layer separating the InAs semiconductor QDs.
A more prolonged annealing at an elevated temperature (760°C) in an atmosphere of hydrogen causes a further increase in the
As metallic QDs’ size to 20–25 nm and their spatial displacement into the region between the coupled InAs semiconductor QDs. 相似文献
20.
R. Heitz I. Mukhametzhanov A. Madhukar A. Hoffmann D. Bimberg 《Journal of Electronic Materials》1999,28(5):520-527
We report photoluminescence (PL), time-resolved PL, and PL excitation experiments on InAs/GaAs quantum dots (QDs) of different
size as a function of temperature. The results indicate that both the inhomogeneous properties of the ensemble and the intrinsic
properties of single QDs are important in understanding the temperature-dependence of the optical properties. With increasing
temperature, excitons are shown to assume a local equilibrium distribution between the localized QD states, whereas the formation
of a position-independent Fermi-level is prevented by carrier-loss to the barrier dominating thermally stimulated lateral
carrier transfer. The carrier capture rate is found to decrease with increasing temperature and, at room temperature, long
escape-limited ground state lifetimes of some 10 ps are estimated. PL spectra excited resonantly in the ground state transition
show matching ground state absorption and emission, indicating the intrinsic nature of exciton recombination in the QDs. Finally,
the PL excitation spectra are shown to reveal size-selectively the QD absorption, demonstrating the quantum-size effect of
the excited state splitting. 相似文献