Compositional and Structural Properties of TiO2-xNx Thin Films Deposited by Radio-Frequency Magnetron Sputtering

TiO2-xNx thin films are deposited onto Si（100） and quartz substrates by arf magnetron sputtering method using a titanium metal disc as a target in Ar, N2, and 02 atmospheres. The substrate temperature is kept at 300℃. The O2 and Ar gas flow rates are kept to be constants and the N gas flow rate is varied. TiO2-xNx films with different N contents are characterized by x-ray diffraction and x-ray photoelectron spectroscopy. The results indicate that the TiO2-xNx thin films can be obtained at 13% N and 15% N contents in the film, and the films with mixed TiO2 and TiN crystal can be obtained at 13% N and 15% N contents in the film. In terms of the results of x-ray photoelectron spectroscopy, N ls of β-N （396 eV） is the main component in the TiO2-xNx thin films. Because the energy level of β-N is positioned above the valence-band maximum of TiO2, an effective optical-energy gap decreases from 2.8 eV （for pure TiO2 film deposited by the same rf sputtering system） to 2.3 eV, which is verified by the optical-absorption spectra.     

ZnCdSe量子阱/CdSe量子点耦合结构中的激子隧穿过程

用室温光致发光谱和飞秒脉冲抽运探测方法对不同垒宽的ZnCdSe量子阱/ZnSe/CdSe 量子点新型耦合结构中激子隧穿过程进行研究，观察到激子从量子阱到量子点的快速隧穿过 程.在ZnSe垒宽为10nm, 15nm, 20nm时，测得激子隧穿时间分别为1.8ps, 4.4ps, 39ps. 关键词： ZnCdSe量子阱 CdSe量子点 激子 隧穿     

Temperature－Dependent Photoluminescence of ZnTe Films Grown on Si Substrates

ZnTe films have been prepared on Si substrates by metal-organic chemical vapour deposition (MOCVD), and the temperature-dependent photoluminescence (PL) properties were investigated. The near-band-edge (NBE) emission of the ZnTe sample at 83K shows an asymmetry line shape, which can be decomposed into two Gaus-siam lines labelled by FE and BE. Temperature-dependent PL intensity of the NBE peak shows two variation regions, and an expression with two dissociation channels fits well to the experimental data. The results of the temperature-dependent full width at half maximum (FWHM) and peak energy were well understood under the framework of the two-dissociation-channel model. That is, at low temperature, the emission from bound excitons governs the NBE peak, while above 157K, the free exciton emission becomes dominant gradually. A simple model with three energy levels was employed to describe the variation in emission intensity of BE and FE with temperature.     

用荧光粉转换方法制备纯绿色LED

采用荧光粉转换的方法制备了纯绿色LED，所制备的纯绿光LED的发光峰值在520nm，其半峰宽约为30nm,法向光强为600mcd。     

(CdZnTe,ZnSeTe)/ZnTe复合量子阱中的超快速激子衰减

为了研究低维半导体结构中的激子过程，并进一步实现超快速的激子衰减，设计了一种新型的(CdZnTe，ZnSeTe)／ZnTe复合量子阱结构，并用低压金属有机化学气相沉积方法(LPMOCVD)制备出来。用泵浦-探测方法，采用反射式光路测量了该复合结构中CdZnTe／ZnTe量子阱的激子衰减。单指数衰减拟合给690fs的下降沿时间。     

m面蓝宝石上ZnO/ZnMgO多量子阱的制备及发光特性研究

利用等离子体辅助分子束外延设备(P-MBE)在m面的蓝宝石(m-Al₂O₃)衬底上制备了ZnO/Zn_0.85Mg_0.15O多量子阱.反射式高能电子衍射谱(RHEED)图样的原位观察表明,多量子阱结构是以二维模式生长的.从光致发光谱中可以看到ZnO/Zn_0.85Mg_0.15O多量子阱在室温仍具有明显的量子限域效应.在290 K时阱宽为3 nm的ZnO/Zn_{0.85关键词： 等离子体辅助分子束外延 ZnO多量子阱 光致发光}     

热处理对立方相结构Mg0.57Zn0.43O合金薄膜表面和组成的影响

MgZnO合金具有可覆盖日盲紫外波段的禁带宽度和晶格匹配的单晶衬底,是理想的日盲紫外探测材料.由于MgO和ZnO分属立方相和六角相,分相问题使高质量单一相MgZnO难以获得.热处理是提高薄膜结晶质量的有效手段.利用MOCVD方法制备了单一立方相Mg0.57Zn0.43O合金薄膜,研究了薄膜的退火行为对薄膜结构和光学性能...     

ZnO/Ag/ZnO多层结构薄膜的光电性质

通过磁控溅射方法生长了不同银层厚度的ZnO/Ag/ZnO多层结构的薄膜,并对其形貌、光吸收谱、光致发光和光响应特性进行了比较研究.结果表明ZnO薄膜中银薄层的加入使得光致发光的强度增强.银层厚度为6 nm样品制成的器件在350 nm处的光响应度为0.06 A/W,相对于ZnO薄膜提高了一个数量级.而当银层厚度达到15 ...     

Boosting the performance of crossed ZnO microwire UV photodetector by mechanical contact homo-interface barrier

One-dimensional (1D) micro/nanowires of wide band gap semiconductors have become one of the most promising blocks of high-performance photodetectors. However, in the axial direction of micro/nanowires, the carriers can transport freely driven by an external electric field, which usually produces large dark current and low detectivity. Here, an UV photodetector built from three cross-intersecting ZnO microwires with double homo-interfaces is demonstrated by the chemical vapor deposition and physical transfer techniques. Compared with the reference device without interface, the dark current of this ZnO double-interface photodetector is significantly reduced by nearly 5 orders of magnitude, while the responsivity decreases slightly, thereby greatly improving the normalized photocurrent-to-dark current ratio. In addition, ZnO double-interface photodetector exhibits a much faster response speed (～ 0.65 s) than the no-interface device (～ 95 s). The improved performance is attributed to the potential barriers at the microwire—microwire homo-interfaces, which can regulate the carrier transport. Our findings in this work provide a promising approach for the design and development of high-performance photodetectors.     

氧化锌基材料、异质结构及光电器件

Ⅱ-Ⅵ族直接带隙化合物半导体氧化锌（ZnO）的禁带宽度为3.37 eV,室温下激子束缚能高达60 meV,远高于室温热离化能（26 meV）,是制造高效率短波长探测、发光和激光器件的理想材料。历经10年的发展,ZnO基半导体的研究在薄膜生长、杂质调控和器件应用等方面的研究获得了巨大的进展。本文主要介绍了以国家“973”项目（2011CB302000）研究团队为主体,在上述方面所取得的研究进展,同时概述国际相关研究,主要包括衬底级ZnO单晶的生长,ZnO薄膜的同质、异质外延,表面/界面工程,异质结电子输运性质、合金能带工程,p型掺杂薄膜的杂质调控,以及基于上述结果的探测、发光和激光器件等的研究进展。迄今为止,该团队已经实现了薄膜同质外延的二维生长、硅衬底上高质量异质外延、基于MgZnO合金薄膜的日盲紫外探测器、可重复的p型掺杂、可连续工作数十小时的同质结紫外发光管以及模式可控的异质结微纳紫外激光器件等重大成果。本文针对这些研究内容中存在的问题和困难加以剖析并探索新的研究途径,期望能对ZnO材料在未来的实际应用起到一定的促进作用。