共查询到20条相似文献,搜索用时 31 毫秒
1.
Huang Wei-qi Liu Shi-rong Qin Chao-jian Cai Shao-hong Xu Li Wu Ke-yue 《Frontiers of Physics in China》2007,2(1):72-75
Some kinds of low-dimensional nanostructures can be formed by the irradiation of laser on a pure silicon sample and SiGe alloy
sample. We have studied the photoluminescence (PL) of the hole-net structure of silicon and the porous structure of SiGe where
the PL intensity at 706 nm and 725 nm wavelength increases obviously. The effect of intensity-enhancing in the PL peaks cannot
be explained within the quantum confinement alone. We propose a mechanism on the increasing PL emission in the above structures,
in which the trap state of the interface between SiO2 and nanocrystal plays an important role.
相似文献
2.
将功率密度约为0.5 J·s-1·cm-2、脉冲宽度约为8 ns、束斑直径为0.045 mm、波长为1 064 nm的YAG激光束照射在硅样品表面打出小孔,在孔内的侧壁上形成较规则的网孔状结构;该结构有很强的光致荧光,其强度比该样品的瑞利散射强;发光峰中心约在700 nm处。在无氧化的环境里用激光加工出的硅样品几乎无发光,这证实了氧在光致荧光增强上起着重要作用。用冷等离子体波模型来解释孔侧壁网孔状结构形成的机理,并用量子受限-发光中心模型来解释纳米网孔壁结构的强荧光效应。当激光辐照时间为9 s时,孔洞侧壁上的网孔状结构较稳定,且有较强的光致荧光。 相似文献
3.
将功率密度约为0.5 J·s-1·cm-2、脉冲宽度约为8 ns、束斑直径为0.045 mm、波长为1 064 nm的YAG激光束照射在硅样品表面打出小孔,在孔内的侧壁上形成较规则的网孔状结构;该结构有很强的光致荧光,其强度比该样品的瑞利散射强;发光峰中心约在700 nm处。在无氧化的环境里用激光加工出的硅样品几乎无发光,这证实了氧在光致荧光增强上起着重要作用。用冷等离子体波模型来解释孔侧壁网孔状结构形成的机理,并用量子受限-发光中心模型来解释纳米网孔壁结构的强荧光效应。当激光辐照时间为9 s时,孔洞侧壁上的网孔状结构较稳定,且有较强的光致荧光。 相似文献
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5.
采用超高真空化学气相淀积系统在SOI(绝缘体上硅)衬底上生长了Si0.82Ge0.18外延层,通过循环氧化/退火工艺,制备出Ge组分从0.24到1的绝缘体上锗硅(SGOI)材料.采用高分辨透射电镜、拉曼散射光谱和光致发光谱表征了其结构及光学性质,对氧化过程中SiGe层中的Ge组分和应变的演变进行了分析.最后制备出11 nm厚的绝缘体上Ge材料(GeOI),具有完整的晶格结构和平整的界面.室温下观测到绝缘体上Ge直接带跃迁光致发光,发光峰值位于1540 nm,发光
关键词:
GeOI
氧化
退火
光致发光谱 相似文献
6.
Enhanced photoluminescence (PL) at room temperature from thermally annealed a-Si:H/SiO2 multilayers is observed through the step-by-step thermal post-treatment. The correlation between the PL and the crystallization process is studied using temperature-dependent PL, Raman, cross section high-resolution transmission electron microscopy (XHRTEM) and x-ray diffraction (XRD) techniques. An intensified PL band around 820 nm is discovered from the sample annealed near the crystallization onset temperature, which is composed of two peaks centred at 773 nm and 863 nm, respectively. It is found that the PL band centred at 863 nm is related to the pseudo nanocrystal (p-nc-Si) silicon, and the PL band centred at 773 nm is attributed to Si = O bonds stabilized in the p-nc-Si surface. 相似文献
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9.
Wei-Qi Huang Rong-Tao Zhang Feng Jin Shui-Jie Qin Shi-Rong Liu 《Optics Communications》2008,281(20):5229-5233
Stimulated emission has been observed from oxide structure of silicon when optically excited by 514 nm laser. The photoluminescence (PL) pulse has a Lorentzian shape with a full width at half maximum (FWHM) of 0.5-0.6 nm. The twin peaks at 694 nm and 692 nm are dominated by stimulated emission which can be demonstrated by its threshold behavior and transition from sub-threshold to linear evolution in light emission. The gain coefficient from the evolution of the peak-emission intensity as a function of the optically pumped sample length has been measured. The oxide structure was fabricated by laser irradiation and annealing treatment on silicon. A model for explaining the stimulated emission has been proposed in which the trap states of the interface between oxide of silicon and porous nanocrystal play an important role. 相似文献
10.
《Superlattices and Microstructures》1994,16(1):55-58
We have systematically observed at room temperature the variations of photoluminescence(PL) from porous silicon(PS) with excitation wavelength in a range from 260 to 460nm at 20nm intervals. In the range from 260 to 320nm, the PL spectra for one of the two studied samples show clear double-peak structure. Each spectrum can be fitted by two Gaussian functions with their peaks centered at about 610nm and 710nm, respectively. The peak position and the full width at half maximum of the two Gaussian functions change little with excitation wavelength. The above phenomena seem hard to interpret using the quantum confinement model, but can be understood in the quantum confinement/luminescence centers model (G.G.Qin and Y.Q.Jia, Solid State Commun. 86, 559(1993)), if we suppose that there are two kinds of luminescence centers adsorbed on the surfaces of nane-scale silicon (NS) units or situated in the SiOx layers covering the NS units in PS. 相似文献
11.
Stuart J. Corr Lisa O'Reilly Eoghan P. Dillon Andrew R. Barron Patrick J. McNally 《Journal of Raman spectroscopy : JRS》2011,42(12):2085-2088
Poly(vinylpyrrolidone)‐stabilized silver nanoparticles deposited onto strained‐silicon layers grown on graded Si1−xGex virtual substrates are utilized for selective amplification of the Si–Si vibration mode of strained silicon via surface‐enhanced Raman scattering spectroscopy. This solution‐based technique allows rapid, highly sensitive and accurate characterization of strained silicon whose Raman signal would usually be overshadowed by the underlying bulk SiGe Raman spectra. The analysis was performed on strained silicon samples of thickness 9, 17.5 and 42 nm using a 488 nm Ar+ micro‐Raman excitation source. The quantitative determination of strained‐silicon enhancement factors was also made. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
12.
S. Sali M. Boumaour M. Kechouane S. Kermadi F. Aitamar 《Physica B: Condensed Matter》2012,407(13):2626-2631
A ZnO thin film was successfully synthesized on glass, flat surface and textured silicon substrates by chemical spray deposition. The textured silicon substrate was carried out using two solutions (NaOH/IPA and Na2CO3). Textured with Na2CO3 solution, the sample surface exhibits uniform pyramids with an average height of 5 μm. The properties and morphology of ZnO films were investigated. X-ray diffraction (XRD) spectra revealed a preferred orientation of the ZnO nanocrystalline film along the c-axis where the low value of the tensile strain 0.26% was obtained. SEM images show that all films display a granular, polycrystalline morphology. The morphology of the ZnO layers depends dramatically on the substrate used and follows the contours of the pyramids on the substrate surface. The average reflectance of the textured surface was found to be around 13% and it decreases dramatically to 2.57% after deposition of a ZnO antireflection coating. FT-IR peaks arising from the bonding between Zn–O are clearly represented using a silicon textured surface. A very intense photoluminescence (PL) emission peak is observed for ZnO/textured Si, revealing the good quality of the layer. The PL peak at 380.5 nm (UV emission) and the high-intensity PL peak at 427.5 nm are observed and a high luminescence occurs when using a textured Si substrate. 相似文献
13.
V. P. Martovitsky V. S. Krivobok 《Journal of Experimental and Theoretical Physics》2011,113(2):288-305
It is found that stressed luminescent samples of Si(001)/Si1 − x
Ge
x
/Si with a germanium concentration of up to 16% contain microcracks. In contrast to ordinary cracks, microcracks are characterized
by partial cracks of the substrate that are not perpendicular to the plane of the plate and are detected by specially designed
X-ray analysis techniques. In a 60-nm-thick layer of SiGe with a germanium concentration of 5%, individual microcracks arise
in samples near the edges of the same type, and the traces of these microcracks coincide with the ripple profiles of the corrugated
growth surface. As the germanium concentration increases, first, the number of microcracks near the edges of a sample increases,
while the corrugated growth relief nearly completely disappears, and then microcracks appear even in the central region of
the sample, thus leading to the vanishing of the curvature of the structure in this region without visible signs of plastic
relaxation. At the same time, even a thin (20 nm) layer of SiGe exhibits a layered structure, and diffuse scattering near
the peak of the SiGe layer increases, which points to the presence of fragments of the layer that are misoriented by ±0.015°;
the intensity of the diffuse scattering may amount to 0.5% of the layer intensity. A spatial analysis of the luminescence
of samples with microcracks shows that the emergence of microcracks hardly affects the peak position and the half-width of
the emission line of the SiGe layer. At the same time, the intensity of exciton emission from both the SiGe layer and the
bulk of silicon is significantly (several times) changed when passing to the regions with microcracks. All the phenomena observed
can be accounted for under the assumption that, between the stages of the loss of the plane crystallization front and the
development of plastic relaxation of misfit stresses, there exists an earlier unknown stage of growth in which the concentration
of nonequilibrium vacancies increases by four to five orders of magnitude and then the vacancies condensate into micropores. 相似文献
14.
The photoluminescence and reflectance of porous silicon (PS) with and without hydrocarbon (CHx) deposition fabricated by plasma enhanced chemical vapour deposition (PECVD) technique have been investigated. The PS samples were then, annealed at temperatures between 200 and 800 °C. The influence of thermal annealing on optical properties of the hydrocarbon layer/porous silicon/silicon structure (CHx/PS/Si) was studied by means of photoluminescence (PL) measurements, reflectivity and ellipsometry spectroscopy. The composition of the PS surface was monitored by transmission Fourier transform infrared (FTIR) spectroscopy. Photoluminescence and reflectance measurements were carried out before and after annealing on the carbonized samples for wavelengths between 250 and 1200 nm. A reduction of the reflectance in the ultraviolet region of the spectrum was observed for the hydrocarbon deposited polished silicon samples but an opposite behaviour was found in the case of the CHx/PS ones. From the comparison of the photoluminescence and reflectance spectra, it was found that most of the contribution of the PL in the porous silicon came from its upper interface. The PL and reflectance spectra were found to be opposite to one another. Increasing the annealing temperature reduced the PL intensity and an increase in the ultraviolet reflectance was observed. These observations, consistent with a surface dominated emission process, suggest that the surface state of the PS is the principal determinant of the PL spectrum and the PL efficiency. 相似文献
15.
Samson T. H. Silalahi Q. V. Vu H. Y. Yang K. Pita Yu Mingbin 《Applied Physics A: Materials Science & Processing》2010,98(4):867-871
Controllable size of silicon (Si) nanocrystals can be achieved by a two-step rapid thermal annealing technique consisting
of rapid annealing at 1000°C in nitrogen ambient and rapid oxidation at 600–800°C of a radio frequency magnetron co-sputtered
Si-rich oxide/SiO2 superlattice structure. The photoluminescence (PL) spectra related to Si nanocrystals were observed in the visible range
(600–900 nm). After rapid oxidation, the size of the nanocrystals was reduced and the quality of the Si nanocrystal/SiO2 interface was improved, resulting in a blue shift and an increase of the PL peak intensity. Finally, annealing in air increases
the PL intensity further. 相似文献
16.
L. K. Orlov E. A. Shteinman V. I. Vdovin 《Bulletin of the Russian Academy of Sciences: Physics》2011,75(5):695-698
The light-emitting properties of cubic-lattice silicon carbide SiC films grown on Si(100) and Si(111) substrates with VPE
at low temperatures (T
gr ∼ 700°C) are discussed. Investigations of the grown films reveal a homogeneous nanocrystalline structure involving only the
3C-SiC phase. When the electron subsystem of the structure is excited by a He-Cd laser emitting at λexit = 325 nm, the photoluminescence (PL) spectra contain a rather strong emission band shifted by about 3 eV toward a short-wave
spectral region. At low temperatures, the PL integral curve is split into a set of Lorentz components. The relation between
these components and the peculiarities of the energy spectrum of electrons in the nanocrystalline grains of the silicon carbide
layers is discussed. 相似文献
17.
Z. H. Xiong S. Yuan Z. M. Jiang J. Qin C. W. Pei L. S. Liao X. M. Ding X. Y. Hou Xun Wang 《Journal of luminescence》1998,80(1-4):137-140
Narrow photoluminescence peaks with a full-width at half-maximum of 14–20 nm are obtained from porous silicon microcavities (PSM) fabricated by the electrochemical etching of a Si multilayer grown by molecular beam epitaxy. The microcavity structure contains an active porous silicon layer sandwiched between two distributed porous silicon Bragg reflectors; the latter were fabricated by etching a Si multilayer doped alternatively with high and low boron concentrations. The structural and optical properties of the PSMs are characterised by scanning electron microscopy and photoluminescence (PL). The wavelength of the narrow PL peaks could be tuned in the range of 700–810 nm by altering the optical constants. 相似文献
18.
M. Modreanu M. Gartner E. Aperathitis N. Tomozeiu M. Androulidaki D. Cristea Paul Hurley 《Physica E: Low-dimensional Systems and Nanostructures》2003,16(3-4):461
Structures containing silicon nanocrystals (nc-Si) are very promising for Si-based light-emitting devices. Using a technology compatible with that of silicon, a broader wavelength range of the emitted photoluminescence (PL) was obtained with nc-Si/SiO2 multilayer structures. The main characteristic of these structures is that both layers are light emitters. In this study we report results on a series of nc-Si/SiO2 multilayer periods deposited on 200 nm thermal oxide SiO2/Si substrate. Each period contains around 10 nm silicon thin films obtained by low-pressure chemical vapour deposition at T=625°C and 100 nmSiO2 obtained by atmospheric pressure chemical vapour deposition T=400°C. Optical and microstructural properties of the multilayer structures have been studied by spectroscopic ellipsometry (using the Bruggemann effective medium approximation model for multilayer and multicomponent films), FTIR and UV–visible reflectance spectroscopy. IR spectroscopy revealed the presence of SiOx structural entities in each nc-Si/SiO2 interface. Investigation of the PL spectra (using continuous wave-CW 325 nm and pulsed 266 nm laser excitation) has shown several peaks at 1.7, 2, 2.3, 2.7, 3.2 and 3.7 eV, associated with the PL centres in SiO2, nc-Si and Si–SiO2 interface. Their contribution to the PL spectra depends on the number of layers in the stack. 相似文献
19.
SnO2 thin films undoped and doped with antimony (Sb), erbium (Er) and Si nanocrystals (Si-nc) have been grown on silicon (Si) substrate using sol-gel method. Room-temperature photoluminescence (PL) measurement of undoped SnO2, under excitation at 280 nm, shows only one broad emission at 395 nm, which is related to oxygen vacancies. The PL of Er3+ ions was found to be enhanced after doping SnO2 with Sb and Si-nc. The excitation process of Er is studied and discussed. The calculation of cross-section suggests a sensitisation of Er PL by Si-nc. 相似文献
20.
Amorphous silicon nitride (a-SiNx) films were deposited using plasma-enhanced chemical-vapor deposition (PECVD) and subsequently, thermal annealing processes were performed at 700-1000 °C in the ultra-high vacuum (UHV) condition. A strong photoluminescence (PL) peak induced by luminescent defect centers was observed at 710 nm for the as-deposited sample. When the sample was annealed at 700-1000 °C, the PL peak intensity became about 3-12 times stronger with no shift of the PL peak. To investigate the origin of the change in PL peak intensity after the thermal annealing, Si 2p and N 1s core-level spectra were systematically analyzed by high-resolution photoemission spectroscopy (HRPES) using synchrotron radiation. In particular, N 1s spectra were decomposed with three characteristic nitrogen-bonding states. It is revealed that the nitrogen bonding state with N-Si and NSi2 configurations (denoted as N3) contributes mainly to the change in PL peak intensity. We note that luminescent nitrogen related defect centers such as N4+ and N2° are localized in the state N3. Detailed analysis of the experimental results shows that the state N3 is located in the interface bounded by the region of the nano-sized stoichiometric silicon nitride Si3N4 (denoted as N1) and is considerably influenced by the thermal annealing, which is an appropriate process to cause strong photoluminescence of the related samples as mentioned above. 相似文献