共查询到18条相似文献,搜索用时 156 毫秒
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利用双水电极介质阻挡放电装置,采用光谱方法测量了大气压氩气介质阻挡放电微放电通道 中的电子温度的时间演化.选取波长为69654nm(2P2→1S5),763 51nm(2P6→1S5 ),77242nm(2P2→1S3)的氩原子谱线进行了时间分辨测量.实验 发现在放电期间,电 压波形开始下降,在放电熄灭后又开始上升.高能级为2P2的跃迁(77242nm和 69654nm )比2P6的跃迁76351nm要延迟几十ns.根据其时间分辨谱,估算了微放电中的 电子激发 温度的时间演化,结果表明,电子激发温度并不是一个恒定值,而是随时间变化的.当放电 电流达到最大值,即电子密度达到最大值时,其电子温度并未达到最大值,而经过200ns 后 才达到最大值.
关键词:
大气压介质阻挡放电
发射光谱
电子激发温度
微放电通道 相似文献
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我们利用光荧光(PL)以及时间分辨光谱(TRPL)研究了用MBE生长在GaAs衬底上的GaNAs/GaAs量子阱的激子局域化以及退局域化.研究发现,在低温下用连续光(Cw)激发,由于GaNAs中势振荡所产生的局域激子发光是所测量到光谱的主要发光来源.然而在脉冲激发下,情况完全不同.在高载流子密度激发或者高温下GaNAs/GaAs量子阱中例外,一个高能端的PL峰成为了主要的发光来源.通过研究,我们将这个新的发光峰指认为量子阱中非局域激子复合的PL峰.这个发光峰在温度和激发强度的变化过程中与局域激子相互竞争.我们相信这一过程也是许多文献所报道的在InGaN和AlGaN等氮化物中经常观测到的发光峰位随温度"S"形变化的主要根源. 相似文献
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我们利用光荧光(PL)以及时间分辨光谱(TRPL)研究了用MBE生长在GaAs衬底上的GaNAs/GaAs量子阱的激子局域化以及退局域化。研究发现,在低温下用连续光(CW)激发,由于GaNAs中势振荡所产生的局域激子发光是所测量到光谱的主要发光来源。然而在脉冲激发下,情况完全不同。在高载流子密度激发或者高温下GaNAs/GaAs量子阱中例外,一个高能端的PL峰成为了主要的发光来源。通过研究,我们将这个新的发光峰指认为量子阱中非局域激子复合的PL峰。这个发光峰在温度和激发强度的变化过程中与局域激子相互竞争。我们相信这一过程也是许多文献所报道的在InGaN和AlGaN等氮化物中经常观测到的发光峰位随温度“S”形变化的主要根源。 相似文献
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用脉冲激光沉积(PLD)法在不同温度的Si(111)衬底上成功制备了c轴择优取向的Mg005Zn095O薄膜.通过X射线衍射(XRD)和光致发光谱(PL)研究了衬底温度对Mg005Zn095O薄膜结构和发光特性的影响,探讨了薄膜的结晶质量与发光特性之间的关系.结果表明,在衬底温度为450℃时生长的Mg005Zn095O薄膜具有很好的c轴取向和较强的光致发光峰.室温下分别用激发波长为240,300和325nm的氙灯作为激发光源得到不同样品的PL谱,分析表明紫外发光峰和紫峰来源于自由激子的复合辐射且发光强度与薄膜的结晶质量密切相关,蓝绿发光峰与氧空位有关.此外,探讨了衬底温度影响紫外光致发光峰红移和蓝移的可能机理.
关键词:
005Zn095O薄膜')" href="#">Mg005Zn095O薄膜
PLD
衬底温度
光致发光 相似文献
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II-VI和III-V族高失配合金半导体是新型高效中间带太阳电池的优选材料体系,但中间带的形成及其能带调控等关键问题仍未得到有效解决.采用氧离子注入方式,在非平衡条件下对碲化锌(Zn Te)单晶材料实现了等电子掺杂,深入研究了离子注入对Zn Te:O材料的微观结构和光学特性的影响.研究表明:注入合适浓度的氧离子(2.5×1018cm-3)将会形成晶格应变,并诱导1.80 e V(导带下0.45 e V)中间带的产生;而较高浓度(2.5×1020cm-3)的氧离子会导致Zn Te注入层表面非晶化,并增强与锌空位相关的深能级(~1.6 e V)发光.时间分辨光致发光结果显示,离子注入诱导形成的中间带主要是和氧等电子陷阱束缚的局域激子发光有关,载流子衰减寿命较长(129 ps).因此,需要降低晶格紊乱度和合金无序,实现电子局域态向扩展态的转变,从而有效调控中间带能带结构. 相似文献
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应用电容-电压、光致荧光和深能级瞬态谱技术研究了分子束外延生长的n型Al掺杂ZnS1-xTex外延层深中心.Al掺杂ZnS0.977Te0.023的光致荧光强度明显低于不掺杂的ZnS0.977Te0.023,这表明一部分Al原子形成非辐射深中心.Al掺杂ZnS1-xTex(x=0,0.017,0.04和0.046)的深能级瞬态傅里叶
关键词: 相似文献
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Carrier recombination dynamics in AlInGaN alloy has been studied by photoluminescence (PL) and time-resolved PL (TRPL) at various temperatures. The fast red-shift of PL peak energy is observed and well fitted by a physical model considering the thermal activation and transfer processes. This result provides evidence for the exciton localization in the quantum dot (QD)-like potentials in our AlInGaN alloy. The TRPL signals are found to be described by a stretched exponential function of exp[(−t/τ)β], indicating the presence of a significant disorder in the material. The disorder is attributed to a randomly distributed QDs or clusters caused by indium fluctuations. By studying the dependence of the dispersive exponent β on temperature and emission energy, we suggest that the exciton hopping dominate the diffusion of carriers localized in the disordered QDs. Furthermore, the localized states are found to have 0D density of states up to 250 K, since the radiative lifetime remains almost unchanged with increasing temperature. 相似文献
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The photoluminescence, photoconductivity and absorption in GaSe0.9Te0.1 alloy crystals have been investigated as a function of temperature and external electric field. It has been observed that the exciton peaks shift to lower energy in GaSe0.9Te0.1 alloy crystals compared to GaSe crystals. The long wavelength tails of interband photoluminescence, photoconductivity and absorption spectra are determined by the free exciton states and show an Urbach-Martienssen-type dependence to the photon energy. The maxima of the extrinsic photoluminescence and photoconductivity spectra were found to be determined by the acceptor centers with an energy of EA=EV+0.19 eV formed by the polytypism and defects complexes that include Se and Te anions. 相似文献
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We employ photoluminescence (PL) and time-resolved PL to study exciton localization effect in InGaN epilayers.By measuring the exciton decay time as a function of the monitored emission energy at different temperatures,we have found unusual behaviour of the energy dependence in the PL decay process. At low temperature, the measured PL decay time increases with the emission energy. It decreases with the emission energy at 200K, and remains nearly constant at the intermediate temperature of 12OK. We have studied the dot size effect on the radiative recombination time by calculating the temperature dependence of the exciton recombination lifetime in quantum dots, and have found that the observed behaviour can be well correlated to the exciton localization in quantum dots. This suggestion is further supported by steady state PL results. 相似文献
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The tunability of the emission energy, oscillator strength and photoluminescence (PL) efficiency by varying the well thickness and excitation density was demonstrated in the ZnSe0.8Te0.2/ZnSe multiple quantum wells. A significant blueshift about 260 meV of the PL peak energy was observed as the well width decreased from 5 to 1 nm. An extraordinary long lifetime (300 ns) of the recombination for the widest sample was detected. The binding energy of the indirect excitons is determined as 12 meV for the thinnest sample. The reduction of PL efficiency by thermal energy is greatly suppressed by employing a high excitation power. 相似文献
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A. A. Klochikhin S. A. Permogorov A. N. Reznitskii 《Journal of Experimental and Theoretical Physics》1999,88(3):574-585
We propose an approach to describing the density of fluctuation states in a disordered solid solution with a strong perturbation
introduced by isoelectronic substitution in the range of attraction-center concentrations below the threshold of percolation
along the sites of a disordered sublattice. To estimate the number of localized states we use the results of lattice percolation
theory. We describe a method for distinguishing, within the continuum percolation theory, among the various “radiating” states
of the fluctuation-induced tail, states that form the luminescence band at weak excitation. We also establish the position
of the band of radiating states in relation to the absorption band of the excitonic ground state and the mobility edge of
the system. The approach is used to describe the optical spectra of the solid solution ZnSe1−c
Tec, which at low Te concentrations can be interpreted as a system with strong scattering. We take into account the exciton-phonon
interaction and show that the calculated and observed luminescence spectra of localized excitons are in good agreement with
each other.
Zh. éksp. Teor. Fiz. 115, 1039–1062 (March 1999) 相似文献
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H. Conzelmann 《Applied Physics A: Materials Science & Processing》1987,42(1):1-18
Results of luminescence studies on silicon doped with the 3d transition metals are reviewed. Spectra are observed after V, Cr, Mn, Fe, and Cu diffusion. We discuss the problems of center identifications, using the example of the CrB-pair luminescence. Level schemes for the optical transitions are discussed and correlated with electrical level positions of TM defects. Luminescent centers can be divided into two classes: CrB,CrGa, and Mn4 are effective recombination centers with low quantum efficiencies, whereas Fe and Cu associated spectra show characteristics of exciton decay at isoelectronic centers, e.g. show a high quantum efficiency. The phonon structure of the spectra is discussed, and it is shown that the local mode energies of the centers follow a systematic trend. 相似文献