Blue-yellow ZnO homostructural light-emitting diode realized by metalorganic chemical vapor deposition technique

We report on the realization of ZnO homojunction light-emitting diodes (LEDs) fabricated by metalorganic chemical vapor deposition on (0001) ZnO bulk substrate. The p-type ZnO epilayer was formed by nitrogen incorporation using N2O gas as oxidizing and doping sources. Distinct electroluminescence (EL) emissions in the blue and yellow regions were observed at room temperature by the naked eye under forward bias. The EL peak energy coincided with the photoluminescence peak energy of the ZnO epilayer, suggesting that the EL emissions emerge from the ZnO epilayer. In addition, the current-voltage and light output-voltage characteristics of ZnO homojunction LEDs have also been studied. (c) 2006 American Institute of Physics.

VTE法制备γ-LiAlO2／α-Al2O3复合衬底以及腐蚀和退火对其影响

通过气相传输平衡法(VTE)制备了γ-LiAlO2／α-Al2O3复合衬底，使用5％的稀盐酸对其进行腐蚀并在900℃退火72h。利用X射线衍射、偏光显微镜及扫描电镜对复合衬底进行了分析，发现在白宝石α面(11-20)和γ面(1—102)均获得单相多晶的γ-LiAlO2，且后者的择优取向好于前者。腐蚀可以提高样品的择优取向，在5％的稀盐酸中，时间控制在2min左右可获得较好的结果。退火后γ-LiAlO2颗粒质量得到改善，白宝石α面上γ-LiAlO2的质量优于r面上的γ-LiAlO2，两者都出现颗粒长大现象。

Structural and optical properties of a-plane ZnO thin films synthesized on γ-LiAlO2 (302) substrates by low pressure metal-organic chemical vapor deposition

Nonpolar a-plane (1120) ZnO thin films have been fabricated on gamma-LiAlO2 (302) substrates via the low-pressure metal-organic chemical vapor deposition. An obvious intensity variation of the E-2 mode in the Raman spectra indicates that there exhibits in-plane optical anisotropy in the a-plane ZnO thin films. Highly-oriented uniform grains of rectangular shape can be seen from the atomic force microscopy images, which mean that the lateral growth rate of the thin films is also anisotropic. It is demonstrated experimentally that a buffer layer deposited at a low temperature (200 degrees C) can improve the structural and optical properties of the epilayer to a large extent. (c) 2007 Elsevier B.V. All rights reserved.

Characterization of m-plane ZnO thin film on gamma-LiAlO2 (100) substrate by metal-organic chemical vapor deposition

Non-polar (1 (1) over bar 00)m-plane ZnO thin film has been prepared on gamma-LiAlO2 (100)substrate via the low pressure metal organic chemical vapor deposition. Obvious intensity variation of the E-2 mode in the polarized Raman spectra and the absorption edge shift in the polarized optical transmission spectra indicate that the m-plane film exhibits optical anisotropy, which have applications in certain optical devices, such as the UV modulator and polarization-dependent beam switch. From the atomic force microscopy images, highly-oriented uniform-sized grains of rectangular shape were observed. (c) 2008 Elsevier B.V. All rights reserved.

Electrical transport in metallic films

On the basis of the Boltzmann equation, the authors propose a model that includes scattering from both film surfaces and grain boundaries, and have studied the quasiclassical electrical transport in metallic films. The in-plane electric conductivity of metallic films is obtained, and the theoretical results are shown to be in good agreement with experimental data. We also give the relation between temperature coefficient of resistivity and thickness of metallic films and make a comparison with experiment. <(C)> 2004 American Institute of Physics.