ZnO粉末的直流电致发光特性研究

用溶胶凝胶法制备了几种ZnO粉末, 测量了它们的直流电致发光. 在样品中观察到了较强的绿带（556 nm）发射; 对十二胺处理的样品, 绿带发光强度最高可提高8倍, 十八胺处理的样品, 绿带发光强度最高可提高12倍. 在同电压下, 十八胺处理的ZnO的发光强度也较十二胺处理的ZnO的发光强度大1.5～2倍; 并在十二胺处理的样品中, 还观察到了强度较小的蓝光谱带（406 nm）. 在一定电压范围内, ZnO电致发光强度随直流电压增强而线性增强. 所得ZnO样品在2V/μm场强下起亮, 在测量的近1 h内, 发光强度稳定, 重复性好. 分析认为：406 nm处的蓝光谱带是由于VZn空位在禁带中（距离价带0.3 eV）形成缺陷能级, 从导带到价带跃迁的结果, 而556 nm处的绿色发射带是由ZnO中氧空位所导致.     

Electroluminescence from Si／SiO2 films deposited on p—Si substrates

The structure of Au/Si/SiO₂/p-Si has been fabricated using the magnetron sputtering technique. It has a very good rectifying behaviour. Visible electroluminescence (EL) has been observed from the Au/Si/SiO₂/p-Si structure at a forward bias of 5V or larger. A broad band with one peak around 650－660 nm appears in all the EL spectra of the structure. The effects of the thickness of the Si layer in the Si/SiO₂ films and of the input electrical power on EL spectra are studied systematically.     

Photoluminescence of a ZnO/GaN Heterostructure Interface

Growth of a ZnO/GaN heterostructure is carried out using pulsed laser deposition. By etching the ZnO layer from the ZnO/GaN structure, the photoluminescence （PL） of the associated GaN layer shows that the donor- acceptor luminescence of CaN shifts to about 3.27eV, which is consistent with the electroluminescence （EL） of n-ZnO/p-GaN already reported. XPS shows that oxygen diffuses into the CaN crystal lattice from the surface to 20nm depth. The PL spectra at different temperatures and excitation densities show that oxygen plays the role of potential fluctuation. The associated PL results of the interface in these LEDs could be helpful to understand the mechanism of EL spectra for ZnO/CaN p-n junctions.     

Electroluminescence from thin SiO2 layers after Si- and C-coimplantation

In this paper we explore the electroluminescence (EL) properties of thermally grown 350 nm thick SiO₂ layers co-implanted with Si⁺ and C⁺ ions. The implanted fluences were chosen in such a way that peak concentrations of excess Si and C of 5–10 at% were achieved. The devices show a broad photoluminescence (PL) between 2.0 and 3.2 eV with a main peak around 2.7 eV. The broad EL spectra show additional peaks around 3.3 eV and between 2.1 and 2.5 eV which are decreased with increasing Si/C concentration. The shape of the EL spectra does not change with increasing injection currents which implies that various types of defects occur for the different concentrations. The device stability is improved in comparison to Ge or Sn implanted oxide layers.     

A comparative study of electroluminescence from Ge／SiO2 and Si／SiO2 films

Ge/SiO_2 and Si/SiO_2 films were deposited using the two-target alternation magnetron sputtering technique. The Au/Ge/SiO_2/p-Si and Au/Si/SiO_2/p-Si structures were fabricated and their electroluminescence (EL) characteristics were comparatively studied. Both Au/Ge/SiO_2/p-Si and Au/Si/SiO_2/p-Si structures have rectifying property. All the EL spectra from the two types of the structure have peak positions around 650－660 nm. The EL mechanisms of the structures are discussed.     

ZnS:Ho3+和ZnS:HoF3交流电致发光薄膜发光特性的研究

利用高真空条件,分舟蒸发制备ZnS:Ho3+和ZnS:HoF3绿色交流电致发光薄膜屏。讨论了ZnS:Ho3+及ZnS:HoF3薄膜的发光特性和光谱差异。确定其激发机理为热电子直接碰撞激发,以及660nm的发射在低浓度下来自于5F3→5I7的跃迁。并认为在两种材料中,由于热电子在外电场中的加速过程中受到不同散射中心的散射,改变了热电子的统计分布,从而直接引起两种材料发射光谱的明显差异。     

Voltage-controlled electroluminescence from SiO2 films containing Ge nanocrystals and its mechanism

Luminescent SiO₂ films containing Ge nanocrystals are fabricated by using Ge ion implantation, and metal–oxide–semiconductor structures employing these films as the active layers show yellow electroluminescence (EL) under both forward and reverse biases. The EL spectra are strongly dependent on the applied voltage, but slightly on the mean size of Ge nanocrystals. When the forward bias increases towards 30 V, the EL spectral peak shifts from 590 nm to 485 nm. It is assumed that the EL originates from the recombination of injected electrons and holes in Ge nanocrystals near the Si/SiO₂ interface, or through luminescent centers in the SiO₂ matrix near the SiO₂/metal interface. The mismatch of the injection amounts between holes and electrons results in the low EL efficiency. Received: 28 February 2000 / Accepted: 28 March 2000 / Published online: 5 July 2000     

轴向尼泊金甲酯取代的酞菁硅的合成、光谱性质和离体光动力活性

合成了一种轴向尼泊金甲酯取代的酞菁硅,即二(4-甲酯基苯氧基)酞菁硅,并通过IR,NMR,HPLC和元素分析等手段进行了表征。研究了该配合物在不同溶剂中的电子吸收光谱和荧光光谱。结果表明,它在含2%Cremophor EL,20%丙二醇的生理盐水中,以单体形式存在,Q带最大吸收位于683 nm附近,相应的摩尔吸光系数为7.47×104mol-1.L.cm-1,最大发射带位于690 nm附近,荧光量子产率为0.34,荧光寿命为4.7 ns。初步的离体光动力活性测试表明,该配合物对B16黑色素瘤细胞具有光动力灭活能力,半致死量LD50为1.2×10-4mol.L-1。     

Evaluation of polarization field in InGaN/GaN multiple quantum well structures by using electroluminescence spectra shift

In order to investigate the inherent polarization intensity in InGaN/GaN multiple quantum well(MQW) structures,the electroluminescence(EL) spectra of three samples with different GaN barrier thicknesses of 21.3 nm, 11.4 nm, and 6.5 nm are experimentally studied. All of the EL spectra present a similar blue-shift under the low-level current injection,and then turns to a red-shift tendency when the current increases to a specific value, which is defined as the turning point.The value of this turning point differs from one another for the three InGaN/GaN MQW samples. Sample A, which has the GaN barrier thickness of 21.3 nm, shows the highest current injection level at the turning point as well as the largest value of blue-shift. It indicates that sample A has the maximum intensity of the polarization field. The red-shift of the EL spectra results from the vertical electron leakage in InGaN/GaN MQWs and the corresponding self-heating effect under the high-level current injection. As a result, it is an effective approach to evaluate the polarization field in the InGaN/GaN MQW structures by using the injection current level at the turning point and the blue-shift of the EL spectra profiles.     

PECVD纳米晶粒硅薄膜的可见电致发光

在用等离子体增强化学汽相淀积的嵌有纳米晶粒硅薄膜中观测到电致发光．发光谱处在500—800nm之间，它有两个分别位于630—680nm和730nm附近的峰，两个峰的强度与薄膜的电导率有密切关系．根据这种材料的结构特性对载流子的传导通道进行了讨论，并且对发光机制进行了初步解释 关键词：     

Tunability of UV electroluminescence for n-ZnO:Al/n −-ZnO/i-MgO/n-GaN heterostructured light-emitting diodes

n-ZnO:Al/n ^?-ZnO/i-MgO/n-GaN heterostructured diodes have been fabricated by radio frequency magnetron sputtering. The electroluminescence (EL) of the n-ZnO:Al/n ^?-ZnO/i-MgO/n-GaN diodes has been investigated. All EL spectra are dominated by ultraviolet (UV) emission peaked at around 368 nm. However, EL performances of the devices can be tuned through controlling the electrical parameters of ZnO:Al films. With the variation of the ZnO:Al films, EL spectra could evolve into random lasing action from conventional EL. The electrical parameters of the corresponding ZnO:Al films were researched, and the related UV emission mechanism is discussed in terms of the energy-band theory of the heterojunctions.     

Spin injection in the multiple quantum-well LED structure with the Fe/AlOx injector

A spin-injection/-detection device has been fabricated based on the multiple quantum well light emitting diode (LED) structure. It is found that only a broad electroluminescence (EL) peak of a full width at half maximum of 8.6 nm appears at the wavelength of 801 nm in EL spectra with a circular luminescence polarization degree of 18%, despite PL spectra always show three well resolved peaks. The kinetic energy gained by injected electrons and holes in their drift along opposite directions broadens the EL pe...     

Alq_3发光层厚度对有机电致发光器件性能的影响

文章以MoO3为空穴注入层,NPB为空穴传输层,改变发光/电子传输层Alq3的厚度,考察了器件电学和光学性能的变化。结果表明,随着Alq3层增加厚度,器件的电流逐步减小,由此获得Alq3薄膜的电场分布情况;器件发光光谱有少量红移,但长波端明显展宽,短波端强度下降。该文拟合了器件电致发光谱,与实验曲线吻合较好。同时拟合结果也表明,干涉效应主要影响光谱在长波端的强度分布,发光区域分布决定光谱在短波端的强度分布。     

Study of Au/ZnO nanorods Schottky light-emitting diodes grown by low-temperature aqueous chemical method

High quality vertically aligned ZnO nanorods (NRs) were grown by low-temperature aqueous chemical technique on 4H-n-SiC substrates. Schottky light-emitting diodes (LEDs) were fabricated. The current-voltage (I–V) characteristics of Schottky diodes reveal good rectifying behavior. Optical properties of the ZnO nanorods (NRs) were probed by cathodoluminescence (CL) measurements at room temperature complemented with electroluminescence (EL). The room-temperature CL spectra of the ZnO NRs exhibit near band edge (NBE) emission as well as strong deep level emission (DLE) centered at 690 nm. At room temperature the CL spectra intensity of the DLE was enhanced with the increase of the electron beam penetration depth due to the increase of defect concentration at the interface and due to the conversion of self-absorbed UV emission. We observed a variation in the DLE along the nanorod depth. This indicates a relatively lower structural quality near the interface between ZnO NRs and n-SiC substrate. The room-temperature CL spectra of SiC show very weak emission, which confirms that most of the DLE is originating from the ZnO NRs, and SiC has a minute contribution to the emission.     

富硅a-SiOxNy：H薄膜的电致发光特性

采用甚高频等离子体增强化学气相沉积方法制备富硅氮氧化硅(a-SiO_0.35N_0.59:H)薄膜,以这层薄膜作为有源层构建发光二极管。实验结果表明器件在室温下可观测到强的电致红光发射,发光峰在715 nm附近,与其光致发光峰位一致。电致发光谱测量还表明器件开启电压为8 V,器件的电致发光强度随注入电流的增大呈线性递增关系。电流-电压特性分析表明器件的载流子输运机制以Pool-Frenkel(P-F)发射模型为主。结合发光有源层的微结构分析,初步认为电致红光发射来自于电子和空穴通过有源层的带尾态的辐射复合。     

Photoluminescence and electroluminescence studies of polyvinyl carbazole films

Polyvinyl carbazole (PVK) film has been prepared by solution method. Its absorption, photoluminescence (PL) and electroluminescence (EL) have been studied. For PL and absorption studies, film of PVK was prepared by spreading PVK solution on clean glass plate. The dried film was taken out of the glass plate and used for absorption, thickness measurement and PL studies. The film is transparent in the visible region and absorption starts at 340 nm wavelength. The absorption peaks are obtained at 280, 250 and 220 nm, indicating that optical gap of film is 3.65 eV and molecular orbitals exist at 4.43, 4.96 and 5.64 eV. PL studies reveal that excitation by violet light gives luminescence at 430, 480 and 690 nm. For EL studies, cell is prepared by depositing PVK film on a portion of conducting glass plate and taking aluminum foil as second electrode. It is observed from the characteristics that the current varies linearly, where as EL intensity varies non-linearly with increasing voltage. Higher brightness has been observed at higher frequencies. EL spectrum shows a sharp peak at 400 nm and a broad and less intense peak at 700 nm, which are attributed to radiative decay of singlet exciton and defect centers, respectively.     

铕高分子配合物红色薄膜电致发光特性

合成了三价铕的高分子配合物,主链高分子采用丙烯酸和甲基丙烯酸甲酯的共聚物,引入邻菲咯啉（ｐｈｅｎ）和二苯甲酰基甲烷（ＤＢＭ）作为第二配体。研制了结构为ＩＴＯ／ＰＶＫ／Ｅｒ＾３＋－ｐｏｌｙｍｅｒ／Ａｌ的器件,起亮电压为８．５Ｖ,在１６Ｖ下看到了明显的红色发光。研究了它的光致发光和电致发光性质,发现电致发光和光致发光的光谱有显示不同的特征,对其可能的机理作了探讨。     

Electroluminescence from modulation-doped pseudomorphic AlGaAs/InGaAs/GaAs quantum wells

Low-temperature electroluminescence (EL) is observed in n-type modulation-doped AlGaAs/InGaAs/GaAs quantum well samples by applying a positive voltage between the semitransparent Au gate and alloyed Au-Ge Ohmic contacts made on the top surface of the samples. We attribute impact ionization in the InGaAs QW to the observed EL from the samples. A redshift in the EL spectra is observed with increasing gate bias. The observed redshift in the EL spectra is attributed to the band gap renormalization due to many-body effects and quantum-confined Stark effect.     

Origin of strong white electroluminescence from dense Si nanodots embedded in silicon nitride

Strong white electroluminescence (EL) from SiN-based devices containing Si nanodots with a density of more than 4.6×10(12)cm(2) was investigated. The white EL illustrates enhanced light emission with increasing applied voltage and can be divided into two components, a dominant peak at ~710 nm and weak one at ~550 nm, which are close to those of the PL spectra optically pumped by the 325 and 488 nm lines, respectively. Based on the PL characteristics, we propose that the dominant EL band arises from the band-to-band recombination in the dense Si nanodots where quantum confinement plays a decisive role in the light emission, whereas the weak EL band originates from the radiative Si dangling bond (K⁰) centers in the silicon nitride matrix.     

ZnO Nanorods Produced by the Method of Arc Discharge

ZnO nanorods are fabricated by arc discharge with ZnO powder as source materials. The sample is characterized by x-ray diffraction, Raman scattering spectra, scanning electron microscopy and high-resolution transmission electron microscopy. The ZnO nanorods exhibit single crystals with the hexagonal wurtzite structure. Many of them are tetrapod-like. The diameters range from several nanometres to about lOOnm, and the main diameters of the nanorods is around 20nm. The length-to-diameter ratio is more than 5, and the grown directions are along the [001] axis. Photoluminescence spectra show a narrow ultraviolet emission at around 389nm and a broad green emission at around 520 nm. The growth process can be interpreted by the vapour-solid mechanism.