MgO相分离对MgxZn1-xO纳米粉体结构和光学性能的影响

采用溶胶-凝胶法制备了MgxZn1-xO(x=0,0.1,0.2,0.3,0.4,0.5)纳米粉体。X射线衍射谱表明:在较高的温度(850℃以上)下退火,MgxZn1-xO纳米粉体从单一的纤锌矿结构相中分离出MgO相的掺杂浓度x约为0.13,且随着x的增加,MgO相含量呈指数型增长。室温光致发光谱显示:MgO相分离对紫外与绿光发射的相对强度有直接的影响,随着MgO相分离的出现,紫外发光峰蓝移,并随着MgO相的增加,紫外发光峰的强度受抑,绿光发光峰变强。样品的室温透过率显示:MgxZn1-xO的禁带宽度在x=0.1时达到最大值并受MgO相分离的影响而减小。     

大学物理教学与考核模式改革实践

本文就我校某大班大学物理教学与考核模式改革实践进行总结,以期能够积累学生参加课堂教学的相关经验,为迎接"MOOCs"的到来,为学生设计出更适宜的教学方法与考核模式做好前期的调研和准备.     

Electrical and optical properties of Sb-doped ZnO thin films synthesized by sol–gel method

Sb-doped ZnO thin films with different values of Sb content （from 0 to 1.1 at.%） are deposited by the sol-gel dip- coating method under different sol concentrations. The effects of Sb-doping content, sol concentration, and annealing ambient on the structural, optical, and electrical properties of ZnO films are investigated. The results of the X-ray diffraction and ultraviolet-visible spectroscopy （UV-VIS） spectrophotometer indicate that each of all the films retains the wurtzite ZnO structure and possesses a preferred orientation along the c axis, with high transmittance （〉 90%） in the visible range. The Hall effect measurements show that the vacuum annealed thin films synthesized in the sol concentration of 0.75 mol/L each have an adjustable n-type electrical conductivity by varying Sb-doping density, and the photoluminescence （PL） spectra revealed that the defect emission （around 450 nm） is predominant. However, the thin films prepared by the sol with a concentration of 0.25 mol/L, despite their poor conductivity, have priority in ultraviolet emission, and the PL peak position shows first a blue-shift and then a red-shift with the increase of the Sb doping content.     

Sn掺杂对ZnO薄膜结构和光电性能的影响

采用溶胶-凝胶浸渍提拉法在玻璃衬底上制备了Sn掺杂ZnO(SZO)薄膜。通过X射线衍射(XRD)和扫描电镜(SEM)研究了Sn掺杂对薄膜表面形貌和微结构的影响。XRD结果表明,所有ZnO薄膜样品都存在(002)择优取向。SEM结果表明随着掺杂浓度的增加,薄膜表面由颗粒向纳米棒转变。电学结果显示掺杂浓度为3at%时,电学性能最好,最低电阻率为6.9×10-2Ω.cm。室温光致发光谱(PL)显示所有的SZO薄膜样品在(325 nm光激发下)380 nm和398 nm两处都有发光峰,随着掺杂浓度的增大,398 nm处的发光强度先增大后减小,然后再增大;380nm处的发光强度始终增大,这些现象与薄膜的表面结构的变化有关。     

基于学研结合大学物理教学平台的创新性理科人才培养

积极探索创新性理科人才培养模式,培养和造就大批基础扎实、专业面向宽、实践能力与创新精神突出的高素质人才是新时期经济社会发展对高等教育发展的迫切要求,也是高等学校人才培养模式改革的重要方向。本文主要从如何有效地通过开展教学改革,着力提高教学质量,培养创新人才等方面介绍西北工大学大学物理教学团队与体系、教材与学研结合大学物理教学平台的建设情况,同时介绍依托学研结合大学物理教学平台创新性理科人才培养路径以及取得的初步成效。     

Numerical study on the dependence of ZnO thin-film transistor characteristics on grain boundary position

The dependence of transistor characteristics on grain boundary(GB) position in short-channel ZnO thin film transistors(TFTs) has been investigated using two-dimensional numerical simulations.To simulate the device accurately,both tail states and deep-level states are taken into consideration.It is shown that both the transfer and output characteristics of ZnO TFTs change dramatically with varying GB position,which is different from polycrystalline Si(poly-Si) TFTs.By analysing the mechanism of the carrier transportation in the device,it is revealed that the dependence is derived from the degrees of carrier concentration descent and mobility variation with GB position.     

退火气氛和镧掺杂浓度对ZnO薄膜结构和光学性能的影响

采用溶胶-凝胶浸渍提拉法在玻璃衬底上制备Zn1-xLaxO(x=0～0.04)(LZO)薄膜,分别在空气、氮气和氩气条件下进行退火,探讨了不同退火气氛和不同镧掺杂浓度对其结构和光学性能的影响.XRD和SEM结果表明:氩气退火条件下ZnO的晶粒尺寸比空气退火条件下和氮气退火条件下的晶粒尺寸略小,且ZnO晶粒的尺寸随着镧掺杂浓度的增加而减小.薄膜光致发光(PL)测量表明:紫光发光带中心在氩气下退火相对于空气下退火存在略微的蓝移,而在氮气下退火则相反;ZnO紫光发光带的位置随着镧掺杂浓度的增加先红移而后蓝移.禁带宽度在镧掺杂量为2;时达到最小值,说明镧可以有效地调节ZnO的禁带宽度.     

Structures and physical properties of R_2TX_3 compounds

Rare-earth compounds have been an attractive subject based on the unique electronic structures of the rare-earth elements. Novel ternary intermetallic compounds R2TX3 (R = rare-earth element or U, T = transition-metal element, X = Si, Ge, Ga, In) are a significant branch of this research field due to their complex and intriguing physical properties, such as magnetic order at low temperature, spin-glass behavior, Kondo effect, heavy fermion behavior, and so on. The unique physical properties of R2TX3 compounds are related to distinctive electronic structures, crystal structures, micro-interaction, and external environment. Most R2TX3 compounds crystallize in AlB2-type or derived AlB2-type structures and exhibit many similar properties. This paper gives a concise review of the structures and physical properties of these compounds. Spin glass, magnetic susceptibility, resistivity, and specific heat of R2TX3 compounds are discussed.