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1.
Lu TC Ke MY Yang SC Cheng YW Chen LY Lin GJ Lu YH He JH Kuo HC Huang J 《Optics letters》2010,35(24):4109-4111
Low-temperature electroluminescence from ZnO nanowire light-emitting arrays is reported. By inserting a thin MgO current blocking layer in between ZnO nanowire and p-GaN, high-purity UV light emission at wavelength 398 nm was obtained. As the temperature is decreased, contrary to the typical GaN-based light emitting diodes, our device shows a decrease of optical output intensity. The results are associated with various carrier tunneling processes and frozen MgO defects. 相似文献
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采用单源化学气相沉积(SSCVD)法,在石英衬底上以Au为缓冲层,Zn4(OH)2(O2CCH3)6.2H2O为固相源制备ZnO薄膜。SEM和XRD测试ZnO薄膜的微结构,结果表明:相对于SiO2衬底上生长的ZnO薄膜,Au/SiO2衬底上生长的ZnO薄膜具有较好的结晶质量和表面平整度;对制备ZnO薄膜的衬底温度进行了工艺优化,结果表明:500℃时制备的ZnO薄膜颗粒大小均匀,结晶质量较好;通过荧光光谱仪对Au/SiO2衬底上的ZnO薄膜进行光致发光(PL)谱测试,ZnO薄膜在400nm出现紫光发射峰,而没有出现与缺陷相关的深能级发射峰,表明ZnO薄膜具有较好的结晶质量。 相似文献
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Peiliang Chen 《Optics Communications》2010,283(7):1359-1362
We report fairly pure ultraviolet (UV) electroluminescence (EL) from a novel p-Si-based SiOx/ZnO/SiOx (x < 2) double-barrier device. When the device is forward biased with positive voltage applied on the gate electrode of Au film, UV light originated from the near-band-edge emission of ZnO is dominant in the EL spectra, while the defect-related visible emissions are undetectable. In the case of reverse bias, no EL is detected from the device. The mechanisms of EL and carrier transports have been explained in terms of energy band structures under forward and reverse biases. 相似文献
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Ying He Jun-An Wang Xiao-Ban Chen Wen-Fei Zhang Xu-Yu Zeng Qiu-Wen Gu 《Journal of nanoparticle research》2010,12(1):169-176
We present a polymer-complexing soft template technique to construct the ZnO-nanowire/polymer light emitting device prototype
that exhibits blue electrically driven emission with a relatively low-threshold voltage at room temperature in ambient atmosphere,
and the ZnO-nanowire-based LED’s emission wavelength is easily tuned by controlling the applied-excitation voltage. The nearly
vertically aligned ZnO-nanowires with polymer film were used as emissive layers in the devices. The method uses polymer as
binder in the LED device and dispersion medium in the luminescence layer, which stabilizes the quasi-arrays of ZnO nanowires
embedding in a thin polymer film on silicon substrate and passivates the surface of ZnO nanocrystals, to prevent the quenching
of luminescence. Additionally, the measurements of electrical properties showed that ZnO-nanowire/polymer film could significantly
improve the conductivity of the film, which could be attributed to an increase in both Hall mobility and carrier concentration.
The results indicated that the novel technique is a low-cost process for ZnO-based UV or blue light emission and reduces the
requirement for achieving robust p-doping of ZnO film. It suggests that such ZnO-nanowire/polymer-based LEDs will be suitable
for the electro-optical application. 相似文献
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利用溶胶-凝胶法(sol-gel method)制备了ZnO纳米颗粒薄膜(ZnO nanoparticle film),并以此为发光层制备了结构为ITO/ZnO nanoparticle/MEH-PPV/LiF/Al的电致发光器件.通过调整器件发光层厚度,对器件的发光光谱和电学特性进行测试研究,发现该器件在一定的直流电压下可以得到以ZnO近紫外(中心波长390 nm)发光为主的电致发光光谱,显示出较好的ZnO近紫外电致发光特性.对该器件的发光机理进行了一定的研究,认为该器件的发光是基于载流子隧穿. 相似文献
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采用热蒸发法在ZnO缓冲层覆盖着Si衬底上合成了2D叶状的Zn晶枝结构,Zn的晶枝长度约为几十微米,厚度约为200nm,随后Zn晶枝在O2的气氛下热处理,在晶枝表面获得纤细、均匀的ZnO纳米线。晶枝按照无催化、自组装、汽相生长模式生长,晶枝最快生长方向是沿着载气气流的方向释放凝固潜热,XRD分析结果结果显示了Zn纳米线具有六角纤锌矿结构,Zn/ZnO的发光谱显示,在380nm处有一弱的UV近带边发射和中心在505nm处的强绿光发射,绿光发射归因于施主/受主对之间的辐射跃迁。 相似文献
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用等离子体辅助分子束外延的方法生长了n-ZnO/i-MgO/p-GaN异质结发光二极管。I-V测量表明其具有典型的二极管整流特性。电致发光峰位于382nm,通过与n型ZnO和p型GaN的光致发光谱比较,其发光峰位与线形都与ZnO的自由激子发射一致,表明该电致发光来自于ZnO的自由激子发射。通过Anderson模型比较了n-ZnO/i-MgO/p-GaN和n-ZnO/p-GaN异质结的能带示意图,证明了由于MgO层的插入抑制了ZnO向GaN层中的电子注入,且有利于空穴向ZnO层注入,从而实现了ZnO层中的电注入发光。 相似文献
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用CVD两步法在常压下于p型Si(100)衬底上沉积出具有较好择优取向的多晶ZnO薄膜。在325nm波长的光激发下,室温下可观察到显著的紫外光发射(峰值波长381nm)。高温退火后氧空位缺陷浓度增加,出现了一个450~600nm的绿光发光带,发光峰值在510nm。作为比较,用一步法生长的ZnO薄膜结晶质量稍差。在其PL谱中不仅有峰值波长389nm的紫外发射而且还出现了一个很强的蓝光发光中心(峰值波长437nm),退火后同样产生绿光发光带。对这两种绿光发光带的发光机制进行了研究,认为前者源于VO,而后者与OZn有密切的关系。 相似文献
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Peiliang Chen 《Journal of luminescence》2010,130(6):1073-1075
Various metal-insulator-semiconductor (MIS) devices in the form of Au/SiOx(x<2)/Si, Au/AlOy(y<1.5)/Si, Au/SiOx/ZnO and Au/AlOy/ZnO have been fabricated. For each device, once a sufficiently high positive voltage is applied on the Au electrode, the same ultraviolet (UV) emission with a spectrum featuring several specific peaks is detected. Interestingly, such UV emissions related to the MIS devices originate from the external N2 microplasma. It is believed that at the high enough positive voltages the highly energetic electrons emitted out of the Au electrode activate the air to generate the N2 microplasma. 相似文献
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使用准分子脉冲激光沉积(PLD)方法在Si(100)基片上制备了高度c轴取向的MgZnO薄膜。分别使用SEM、XRD、XPS、PL谱和吸收谱表征了薄膜的形貌、结构、成分和光学性质。实验发现氧气压强对MgZnO薄膜的结构和光学性质有重要影响。当氧气压强由5 Pa增大到45 Pa时,薄膜的PL谱紫外峰蓝移了86meV,表明氧气压强的增大提高了MgZnO薄膜中Mg的溶解度。在15 Pa氧气压强下制备的薄膜显示了独特、均匀的六角纳米柱状结构,其PL谱展示了优异的发光特性,具有比其他制备条件下超强的紫外发射和微弱的可见发光。500~600 nm范围内的绿光发射,我们讨论其机理可能源于深能级中与氧相关的缺陷。使用PLD得到纳米柱状结构表明:优化制备条件,可望使用PLD制备ZnO纳米阵列的外延衬底;可使用PLD技术开发基于ZnO纳米结构的高效发光器件。 相似文献
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利用原子层沉积技术制备了具有圆形透明电 极的Ni/Au/Al2O3/n-GaN金属-氧化物-半导体结构, 研究了紫外光照对样品电容特性及深能级界面态的影响, 分析了非理想样品积累区电容随偏压增加而下降的物理起源. 在无光照情形下, 由于极长的电子发射时间与极慢的少数载流子热产生速率, 样品的室温电容-电压扫描曲线表现出典型的深耗尽行为, 且准费米能级之上占据深能级界面态的电子状态保持不变. 当器件受紫外光照射时, 半导体耗尽层内的光生空穴将复合准费米能级之上的深能级界面态电子, 同时还将与氧化层内部的深能级施主态反应. 非理想样品积累区电容的下降可归因于绝缘层漏电导的急剧增大, 其诱发机理可能是与氧化层内的缺陷态及界面质量有关的“charge-to-breakdown”过程.
关键词:
原子层沉积
2O3/n-GaN')" href="#">Al2O3/n-GaN
金属-氧化物-半导体结构
电容特性 相似文献
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M. Gao J. H. Yang L. L. Yang Y. J. Zhang H. L. Liu H. G. Fan J. H. Lang Y. R. Sui B. Feng Y. F. Sun Z. Q. Zhang H. Song 《Applied physics. B, Lasers and optics》2013,112(4):539-545
ZnO/MgO core–shell nanorod arrays were synthesized successfully by the hydrothermal growth method. Photoluminescence (PL) emission from the nanorods showed remarkable enhancement after the growth of the MgO layer. The ZnO/MgO core–shell nanorods are type-I heterostructures, the electrons and holes of which are both confined in the core of the nanorods, as a result, leading to the increase of the photoluminescence intensity in this system. In addition, another reason for the enhancement of PL emission was the deposition of MgO shell suppression of surface defects. In addition, the activation energy (E a) of 63 meV in the ZnO/MgO core–shell nanorods was obtained from temperature-dependent PL. 相似文献
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You-Wei Wang Jian-Ping Xu Hao Wang Shu-Bin Li Qing-Liang Shi Yuan Hong Li-Fang Jiang Hu-Chen Yuan Lan Li 《Applied Physics A: Materials Science & Processing》2014,116(4):1921-1925
In this paper, we fabricated a p-PVK/n-ZnO nanorods (NRs)/p-MEH-PPV dual heterojunctions white light-emitting diode. Relative to previously reported p–n heterojunction structure including ZnO NRs and polymer, the device exhibits a low turn-on voltage of 7 V. An obviously broad electroluminescence emission band, originated from the overlap of PVK emission and ZnO defects emissions, was observed extending from 360 up to 700 nm. The influence of the two introduced p-type polymer layers on the device characteristic is discussed. With its hole conductivity, the p-PVK layer cannot only improve the holes tunnel into ZnO NRs layer, but also lower the barrier between ITO and the valance band of ZnO NRs. On the other hand, p-MEH-PPV could be regarded as block layer for the injection of electrons from the Al electrode. Both of two p-type polymers dramatically improve the injection balance of carriers, leading to a low turn-on voltage. Meanwhile, the carrier transport mechanism of the device under different forward bias region was discussed on the basis of current–voltage curve. 相似文献
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Well-aligned ZnO nanorod arrays were synthesized by low-temperature wet chemical bath deposition (CBD) method on Si substrate under different conditions. Results illustrated that dense ZnO nanorods with hexagonal wurtzite structure were vertically well-aligned and uniformly distributed on the substrate. The effects of precursor concentration, growth temperature and time on nanorods morphology were investigated systematically. The mechanism for the effect of preparation parameters was elucidated based on the chemical process of CBD and basic nucleation theory. It is demonstrated that the controllable growth of well-aligned ZnO nanorods can be realized by readily adjusting the preparation parameters. Strong near-band edge ultraviolet (UV) emission were observed in room temperature photoluminescence (PL) spectra for the samples prepared under optimized parameters, yet the usually observed defect related deep level emissions were nearly undetectable, indicating high optical quality ZnO nanorod arrays could be achieved via this easy process chemical approach at low temperature. 相似文献
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Zhengping Fu Beifang Yang Zhen Wang Hongwei Yan Jian Zuo Xianming Liu 《Solid State Communications》2006,138(4):179-183
By glycine-nitrate combustion route and followed by 900 °C annealing in air, ZnO-MgO nanocomposite with heterojunction-like structures between ZnO and MgO phase was successfully produced. The ultraviolet photoluminescence band from ZnO is enhanced by the incorporation of MgO, as compared to the pure ZnO synthesized via the similar route. The charge transfer required by electronic equilibrium across the junction creates an electron depletion region in ZnO phase, which greatly changes the electron states of visible emission-related defects, as a result, the band-edge emission is enhanced while the visible emission in ZnO is suppressed. This mechanism may provide an effective way to modify the emission property of nanomaterials. 相似文献
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ZnO hexagonal prisms have grown on MgO-coated Si (111) substrates by chemical vapor deposition. The process has two steps : the preparation of MgO-coated Si (111) substrates and the preparation of uniform ZnO hexagonal prisms. Some nucleation sites are provided on the Si substrates by the MgO layers, which have the capability to improve the growth of ZnO prisms in the heteroepitaxy. The prisms are single crystals with a preferential growth along the c axis and they are well-faceted at both the end and side surfaces. Room-temperature photoluminescence measurement of these ZnO prisms have shown a strong ultraviolet (UV) emission band centered at 393 nm and a weak green emission band centered at 507 nm, which may be provide an improvement in novel ultraviolet light-emitting devices. In addition, a possible mechanism for the prism growth is proposed based on the analysis by electron microscopy. 相似文献
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《Physics letters. A》2006,355(3):228-232
We have fabricated a multiply layer SiC/ZnO on Si substrates using the RF-magnetron sputtering technique with the targets of a single crystalline SiC and a polycrystalline ZnO. The as-deposited films were annealed in the temperature range of 600–1000 °C under nitrogen ambient. We have observed a strong ultraviolet (UV) emission (370 nm) from the as-deposited SiC/ZnO film and an intense violet emission (412 nm) from the film annealed at high temperature (1000 °C) under nitrogen ambient. The SiC film quality and the PL intensities are considered to be strongly dependent on the crystalline quality of the ZnO buffer layer. With the increase of the annealing temperature, the crystalline quality of the ZnO buffer layer is improved, resulting in the improvement of the SiC film quality and the increase of the PL intensities. The thin films have been characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) to provide the evidences of photoluminescence (PL). We suggest that the UV emission could be attributed to the nanocrystal silicon particles, that the 395 nm band is related to ZnO buffer layer and has a great relation to the crystalline quality of the ZnO film, and that the violet emission is associated with the emission luminescence from 6H-SiC, which bears on the SiC film quality. The obtained results are expected to have important applications in modern optoelectronic devices. 相似文献