共查询到20条相似文献,搜索用时 15 毫秒
1.
In this work, an unconventional approach for epitaxial growth of Si on single-crystalline rare-earth oxide is presented using molecular beam epitaxy under ultra-high vacuum. Surface and bulk crystalline structures as well as chemical content were examined. Silicon-on-insulator layers were fabricated by encapsulated solid phase epitaxy on Si(111) substrate. The gadolinium oxide capping layer was removed by wet-chemical etching. The remaining silicon layer is single crystalline without any impurities and exhibits 7 × 7 reconstructed surface after annealing in very low silicon flux in the growth chamber. The thermal stability of the fabricated silicon-on-insulator structure was studied by step-wise heating under ultra-high vacuum conditions. The fabricated ultra-thin (10-15 nm) silicon-on-oxide layers remain structurally and chemically stable up to 900 °C. 相似文献
2.
Yaroslav E. Romanyuk Daniel Kreier Kin Man Yu Stephen R. Leone 《Thin solid films》2009,517(24):6512-8628
The effect of silicon nitridation on structural quality, indium incorporation, and electrical properties of the InGaN/Si heterojunctions is investigated. A series of InxGa1 − xN (x = 0-0.32) thin films are grown directly on Si(111) substrates, with and without a SixNy surface layer, by plasma-assisted molecular beam epitaxy. The crystalline quality is higher and the indium incorporation is increased when the InxGa1 − xN thin films are grown with the intentional SixNy buffer. These observations are explained by the reduced local elastic stress at the interface and N-polarity of the surface, both of which promote the incorporation of In. The obtained n-InxGa1 − xN/p-Si (x = 0.2-0.3) heterojunctions exhibit a nearly ohmic behavior, and the series resistance is higher for the SixNy-containing junctions. Our results suggest that unlike the amorphous SixNy region spontaneously formed during direct deposition of III-nitrides on Si, the SixNy layer obtained by high-temperature annealing of Si(111) in nitrogen atmosphere is beneficial to the InxGa1 − xN deposition. 相似文献
3.
We report on the Sb induced modifications of the morphology of self assembled Ge/Si(100) quantum dot stacks in a Si matrix grown by a molecular beam epitaxy. It is shown that the size of the quantum dots in the stack and the Si spacer layer uniformity inside the stack are regulated by the amount of deposited Sb. We consider the thin Sb layer at the Ge/Si growth interface as a factor limiting the surface migration of Si and Ge ad-atoms. The surface diffusion coefficients of Si ad-atom on uncovered pyramid shaped Ge island and on a Ge island covered by a single monolayer of Sb are estimated to be 2.4 μm2s−1 and 2.3 × 10−4 μm2s−1 at a temperature of 600 °C, correspondingly. Based on this remarkable reduction of surface diffusion the morphology of the surface can be preserved when the growth is continued after the single monolayer of Sb is at the surface. 相似文献
4.
The initial growth stages of materials non-active to a substrate has been extensively studied for decades, whereas there had been fewer studies on the initial growth of active metals on silicon substrate, despite its technological importance. In this paper the very early growth stages of transition metal (Ti, V and Nb) films deposited by rf sputtering on unheated (100) Si substrate were studied by in situ X-ray photoelectron spectroscopy. The following sequence of the phase composition and the growth mechanism changes during deposition process was revealed. Initially in a submonolayer regime, small 3D TiO2 islands are formed via reduction of a native silicon oxide layer on a substrate followed by formation of a TiO phase between TiO2 islands and on their top. After deposition of ca. 2 monolayers a metallic Ti phase appears and later only the metal Ti film grows. The same growth behavior takes place at Nb and V deposition with a difference that in the case of Nb the above changes occur at earlier stages what can be explained by the highest niobium activity to the reduction of silicon oxide in the row V, Nb, Ti. 相似文献
5.
T. Tambo S. Konishi S. Takeda N. Yamada H. Ueba C. Tatsuyama 《Thin solid films》1997,300(1-2):223-227
Bi-Sr-Cu-O (BSCO) thin films have been epitaxially grown on cleaned SrTiO3 (001) substrates by a sequentially shutter-controlled molecular beam epitaxy system using an oxygen radical beam. A spot intensity of specular beam in in-situ reflection high-energy electron diffraction (RHEED) was monitored during the atomic layer epitaxy. Atomic force microscopy (AFM) images of the epitaxial thin films were observed in the atmosphere at some oscillation points of the specular beam intensities. The chemical composition ratios of the films (about 100 Å) were determined from intensities of X-ray photoemission spectroscopy. The crystallinity of the films was measured by X-ray diffraction.
The amount of metal deposition corresponding to a half cycle of the intensity oscillation of the specular spot was found to be appropriate to form the flat surface. Characteristic islands were found at the surfaces covered with excess bismuth or excess copper atoms in the AFM image. The intrinsic modulated structure of the BSCO crystal was observed at the surface after the first copper deposition on Sr/Bi/SrTiO3 in the RHEED pattern. 相似文献
6.
7.
In this paper, we report a method of growing of the catalyst-free self-organized ZnMgO nanocolumns with single quantum well on Si (1 1 1) substrates by plasma-assisted molecular beam epitaxy technique (PA-MBE). The structures were grown without buffer layers. Optical properties of the ZnMgO/ZnO/ZnMgO quantum wells were studied by photo (PL)- and cathodoluminescence (CL) spectroscopy. A detailed analysis of the optical properties has been carried out, including quantum confinement effect and temperature dependence of excitonic emission. The structures reveal intense near band edge emission in PL as well as in CL. Blue shift of excitonic emission from the wells in comparison to bulk ZnO due to the quantum confinement effect is observed. Cross-sectional SEM–CL mapping shows that the ZnO/ZnMgO single quantum wells with different well widths are located in ZnMgO nanocolumns. The crystalline quality of the heterostructure was characterized by X-ray diffraction (XRD). No phase separation in ZnO/ZnMgO quantum structures was found. 相似文献
8.
M. Godlewski J. P. Bergman B. Monemar U. Rossner R. Langer A. Barski 《Materials Science and Engineering: B》1997,50(1-3):113-116
We report the observation of bright photoluminescence (PL) emission from two types of GaN epilayers grown by molecular beam epitaxy (MBE). Wurtzite phase GaN/Si (111) epilayers are grown by gas source MBE process, whereas cubic phase GaN epilayers are grown on (001) Si covered by thin SiC film in the process of Si annealing in propane prior to the GaN growth. PL emissions are identified based on the results of detailed PL and time-resolved PL investigations. For the wurtzite phase GaN we observe an efficient up in the energy transfer from bound to free excitons. This process is explained by a large difference in the PL decay times for two types (free and bound (donor, acceptor)) of excitonic PL emissions. For cubic phase GaN we confirm recent suggestion that acceptors have smaller thermal ionization energies than those in the wurtzite phase GaN. 相似文献
9.
The growth of CaF2 films with a thickness of approximately 3–4 nm on well-oriented Si(1 1 1) substrates by molecular beam epitaxy at temperatures between 410 and 560 °C were investigated by ex vacuo atomic force microscopy. Layer-by-layer growth producing atomically flat CaF2 surfaces has been observed in a very narrow growth temperature window between approximately 430 and 470 °C. Perfect triangular shaped islands of one CaF2 layer height are found on the surface with all corners aligned with the Si
directions, indicating a pure B-stacking of the CaF2 film. Surprisingly, also the substrate steps have been overgrown without visible defects. Below 410 °C, two different island orientations revealed a mixture of A- and B-stacking areas in the films. Above 520 °C non-wetting of the CaF interface layer leads to epitaxial films with a rough surface morphology. 相似文献
10.
Properties and applications of MBE grown AlGaN 总被引:1,自引:0,他引:1
M. Stutzmann O. Ambacher A. Cros M. S. Brandt H. Angerer R. Dimitrov N. Reinacher T. Metzger R. Hpler D. Brunner F. Freudenberg R. Handschuh Ch. Deger 《Materials Science and Engineering: B》1997,50(1-3):212-218
AlGaN epitaxial films have been grown on sapphire by plasma-induced molecular beam epitaxy (MBE) over the entire composition range from GaN to AlN. Structural and optical properties of the alloys have been investigated by X-ray diffraction (XRD), transmission electron and atomic force microscopy, Raman scattering, ellipsometry, optical transmission, and subgap absorption spectroscopy. Electron spin resonance has been used to study the dependence of intrinsic paramagnetic defects on Al mole fraction. N- and p-type doping with Si and Mg, respectively is found to become increasingly difficult with increasing Al content because of a continuous shift of the donor and acceptor levels deeper into the bandgap. Apart from the use of AlGaN as cladding layers in light emitting diodes, applications in MODFET transistors, solar blind photodetectors, surface acoustic wave devices and Bragg reflectors appear interesting and will be discussed briefly. 相似文献
11.
O. Maksimov P. Fisher M. Skowronski V.D. Heydemann 《Materials Chemistry and Physics》2006,100(2-3):457-459
GaN films are grown on [0 0 1] GaAs substrates by plasma-assisted molecular beam epitaxy using a three-step process that consists of a substrate nitridation, deposition of a low-temperature buffer layer, and a high-temperature overgrowth. Films are evaluated by X-ray diffraction and the dependence of crystalline quality on the nitridation temperature is studied. It is demonstrated that nitridation has to be performed at low-temperature to achieve c-oriented α-GaN. Higher nitridation temperature promotes formation of mis-oriented domains and β-GaN inclusions 相似文献
12.
The molecular beam epitaxial growth of Si on SiC(0001), exhibiting a Stranski–Krastanov mode, was investigated by reflection high-energy electron diffraction. Several surface superstructures were observed in the initial stage of growth. After exceeding a critical coverage, Si island formation sets in. Under near-equilibrium conditions, the critical coverage was 1.4 monolayers and corresponds to the occurrence of a 3×3 superstructure remaining as a wetting layer after the island formation. Island formation at high deposition rates (R) and low temperatures (T) is kinetically delayed, which can be described as function of R and the diffusivity D by a relationship
. Si islands, which were relatively uniform size of several nm with a density of 1011 cm−2, were obtained under these conditions. At lower R values the critical thickness is only a function of T, indicating that the incorporation time of adatoms is the relevant time scale for surface diffusion. Ordered arrays of small dots were also grown on vicinal surfaces at higher T and lower R values, which can be attributed to a lower diffusivity at step edges, acting as perfect sinks for the Si adatoms. Furthermore, two different kinds of islands were found with a (111)/(0001) and (110)/(0001) epitaxial relationship. 相似文献
13.
Silicon oxide thin films have been deposited in plasma-assisted CVD process. With tetraethylorthosilcate (TEOS, Si(OC2H5)4) as precursor and an oxygen RF-plasma, thin films of 50-100 nm were deposited on silicon wafers. The deposition process was controlled in situ by monitoring the soft X-ray reflectivity of the growing layer. The influence of additional gases such as nitrogen and changes of the plasma conditions on the resulting films have been studied by analyzing the films with grazing incidence X-ray reflectometry, infrared spectroscopy, spectral ellipsometry and capacitance-voltage and current-voltage measurements were performed at different temperatures. 相似文献
14.
G. E. Cirlin N. K. Polyakov V. N. Petrov V. A. Egorov D. V. Denisov B. V. Volovik V. M. Ustinov Zh. I. Alferov N. N. Ledentsov R. Heitz D. Bimberg N. D. Zakharov P. Werner U. Gsele 《Materials Science and Engineering: B》2001,80(1-3):108-111
MBE growth and properties of InAs nanoscale islands formed on silicon are reported. Islands capped with Si emit a photoluminescence band in the 1.3 μm region. Upon annealing at increased substrate temperature, extensive interdiffusion leads to the formation of an InAs solid solution in the Si cap layer. Additionally, InAs-enriched regions with extensions of 6 nm, exhibiting two kinds of ordering, are observed. The ordering of InAs molecules occurs, respectively, in (101) and
planes inclined to (110) and
planes parallel to the [001] growth direction. 相似文献
15.
S. Einfeldt U. Birkle C. Thomas M. Fehrer H. Heinke D. Hommel 《Materials Science and Engineering: B》1997,50(1-3):12-15
The growth of GaN on sapphire by plasma assisted molecular beam epitaxy (MBE) is investigated with the object of optimizing the material quality. The V/III flux ratio as well as the growth temperature are discussed in relation to their impact on electrical, optical and structural layer properties. Samples grown under nearly stoichiometric conditions exhibit both the highest mobilities and the highest photoluminescence efficiencies. Growth temperatures above 800°C were found to result in narrow reflections in X-ray diffraction. However, the chemical decomposition of GaN at temperatures above 850°C limits the suitable temperature range for the growth under high vacuum conditions. 相似文献
16.
Thin film transistor incorporating silicon nitride (SiNx) films deposited by catalytic chemical vapor deposition (Cat-CVD) on silicon exhibit some problems such as a large-threshold voltage shift and a large hysteresis loop width of the capacitance vs. voltage (C–V) characteristics. In this work, in order to solve these problems, the surface of the silicon substrate is catalytically nitrided before SiNx deposition. Inserting the nitridation layer, injection-type hysteresis loop of C–V curve is reduced from 1.3 to 0.05 V and large threshold voltage shift to the negative direction is reduced from 4 to 1.8 V. 相似文献
17.
M. MamatrishatM. Kouda K. Kakushima H. NohiraP. Ahmet Y. KataokaA. Nishiyama K. TsutsuiN. Sugii K. NatoriT. Hattori H. Iwai 《Vacuum》2012,86(10):1513-1516
Interface reactions of a Ce-oxide layer with Si(100) wafers have been characterized by X-ray photoelectron spectroscopy. The ratio of Ce atoms in Ce3+ states within the Ce-oxide layer has been found to decrease from 47% at as-deposited sample to 26% after annealing. From detailed reaction analysis of valence number transitions of Ce atoms and the creation of SiO2 layer at the interface, the reacted Ce3+ atoms are converted into silicates and Ce4+ with a ratio of 2:1. The energy bandgap of Ce-silicate layer has been determined as 7.67 eV and the valence band offset with respect to Si(100) wafer has been extracted as 4.35 eV. 相似文献
18.
本文根据Riber、Veeco、DCA Instruments等著名公司的最新资料简要介绍了世界上主要分子束外延设备制造公司及其主流产品的基本情况,供国内相关领域的读者在了解和选购MBE产品时作参考。 相似文献
19.
A. V. Blant T. S. Cheng N. J. Jeffs C. T. Foxon C. Bailey P. G. Harrison A. J. Dent J. F. W. Mosselmans 《Materials Science and Engineering: B》1997,50(1-3):38-41
We have been studying the structural properties of Group III-Nitrides on Si substrates. We have shown from X-ray data that alloys of (AlGa)N and (InGa)N can be grown by plasma enhanced molecular beam epitaxy on oxidised (100) Si substrates with good control of the composition, over the entire range from InN to AlN. The composition of the alloys deduced from electron probe microanalysis data agree well with those from X-ray measurements assuming Vegard's law is valid for both alloy systems. SIMS studies show that the film composition is uniform in depth. EXAFS studies show no evidence for spinodal decomposition over the entire composition range for the (InGa)N alloys and indicate a monotonic variation in lattice parameter with increasing In mole fraction. 相似文献
20.
ZnO thin films were prepared on Si(0 0 1) substrates using a pulsed laser deposition (PLD) technique and then their growth and properties were investigated particularly as a function of ambient O2 pressure during film growth. It was found that the microstructure, crystallinity, orientation and optical properties of the films grown are strongly dependent on the O2 pressures used. Completely c-axis oriented ZnO films are grown in a low O2 pressure regime (5×10−4-5×10−2 Torr), whereas a randomly oriented film with a much lower crystallinity and a rougher grained-surface is grown at an O2 pressure of 5×10−1 Torr. This deterioration in film quality may be associated with the kinetics of atomic arrangements during deposition. Our results suggest that ambient O2 pressure is an important processing parameter and should be optimized in a narrow regime in order to grow a ZnO film of good properties in PLD process. 相似文献