共查询到20条相似文献,搜索用时 171 毫秒
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报道了利用ZnO和Li2O混合物在5GPa, 1200 ℃—1500 ℃条件下, 制备Li掺杂p型ZnO(记作ZnO: Li)固溶体的过程. 研究发现, 高压下温度对于ZnO: Li固溶体的导电类型以及结构具有较大的影响. 其中在1500 ℃条件下烧结的ZnO: Li(Li的掺杂量4.5%)表现出良好的p型电学性能, 其电阻率为3.1× 10-1Ω·cm, 载流子浓度为3.3× 1019cm-3, 迁移率为27.7cm2·V-1·s-1. 通过实验及理论计算确定了其受主能级为110meV, 讨论了压力对p型ZnO的形成和电学性能的影响. 相似文献
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采用密度泛函理论研究了Li原子掺杂8-羟基喹啉铝(Alq3)分子的几何构型、 前线分子轨道及电子转移特性. 研究结果表明, Li原子掺杂Alq3后, Li原子与Alq3的O, N原子键合, 形成电子转移复合物. Li原子将部分电子转移到Alq3的吡啶环上, 在Alq3的带隙内形成施主能级, 这种n型掺杂结构有效地提高了电子的传输效率; 但过多的Li原子的掺杂会使Alq3分解, 从而减弱其电子传输能力. 为使Alq3的电子传输能力达到最高, Li原子的掺杂应保持在2:1左右的比例. 相似文献
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Ghulam Murtaza Rai Muhammad Azhar Iqbal Yongbing Xu Iain Gordon Will Wen Zhang 《化学物理学报》2011,24(3):353-357
研究Ho3+掺杂对氧化锌半导体材料的微结构和磁学性质影响. 利用热蒸发技术制备了一系列沉积在Si(100)衬底的Zn1-xHoxO(x=0.0、0.04、0.05)薄膜. X射线光谱、表面形貌以及磁性的实验结果表明,Ho3+掺杂对ZnO薄膜材料的性能影响很大. X射线衍射图显示峰位出现高角度转变并且趋向于(101)取向,在ZnO晶格显示Ho3+置换. 扫描电子显微镜和能谱仪对薄膜的表面形貌以及化学 相似文献
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采用密度泛函理论结合投影缀加波方法,对掺杂Cd导致ZnO禁带宽度下降的机理进行了研究. 通过对掺杂前后电子能带结构,态密度以及分态密度的计算和比较,发现CdxZn1-xO价带顶端(VBM)始终由O-2p占据;而导带顶端(CBM)则由Cd-5s与Zn-4s杂化轨道控制. 随着掺杂浓度的增加,决定带隙宽度的CBM的位置下降,同时VBM的位置上升,从而导致了带隙的变窄,出现了红移现象. 此外,Cd掺杂会使晶胞发生膨胀,这种张应变也是导致Cd 相似文献
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利用第一性原理方法, 本文计算了B/N单掺杂SiNWs, 以及含有表面悬挂键的B/N单掺杂硅纳米线的总能和电子结构, 计算结果表明, 悬挂键的出现会导致单原子掺杂失效. 能带结构分析表明, B/N掺杂的H钝化的SiNWs表现出正常的p/n特性, 而表面悬挂键(dangling binding, DB)的存在会导致p型(B原子)或者n型(N原子)掺杂失效; 其失效的原因主要是因为表面悬挂键所引入的缺陷能级俘获了n型杂质(p型杂质)所带来的电子(空穴); 利用小分子(SO2)吸附饱和悬挂键可以起到激活杂质的作用, 进而实现Si纳米线的有效掺杂. 相似文献
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采用溶胶凝胶法在玻璃基片上制备了ZnO及Ni, Fe共掺杂的Zn0.95-xNi0.05FexO (x=0, 0.005, 0.01, 0.03, 0.05) 薄膜. 通过扫描电镜(SEM) 和X射线衍射(XRD) 研究了薄膜样品的表面形貌和晶体结构. 结果表明所有样品都具有(002) 择优取向, Fe掺杂导致ZnO: Ni薄膜的晶体质量变差, 晶粒尺寸减小, 但适当的Fe掺杂有利于获得致密、 均匀的薄膜. XPS测试结果表明样品中Ni离子的价态为+2价, Fe离子的价态为+2价和+3价.室温光致发光(PL) 测量表明, 所有样品均观察到较强的紫外发光峰, 蓝光双峰和绿光发光峰. ZnO: Ni薄膜的发光强度可以通过Fe掺杂进行有效调节. 进而我们讨论了Ni, Fe共掺杂ZnO样品的发光机理. 相似文献
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X.-Y. Duan R.-H. Yao Y.-J. Zhao 《Applied Physics A: Materials Science & Processing》2008,91(3):467-472
The formation of single defects and defect complexes are investigated in Li, N co-doped ZnO by the first-principles plane
wave method with projector augmented wave (PAW) pseudo-potential technology. We find that: (i) p-type conductivity could be
achieved in single Li doped ZnO under an O-rich condition, since the formation energy of LiZn acceptor is much lower than the interstitial Lii; (ii) the dual-acceptor complex LiZn-NO is unlikely to form, and the good p-type conductivity is mainly attributed to the LiZn acceptor, even in Li, N co-doped ZnO; (iii) the additional introduction of N may help compensate the single Lii donor defects under certain growth conditions, but its role in the p-type conductivity in ZnO remains to be clarified.
PACS 71.15.Mb; 73.61.Ga; 71.15.Nc; 71.20.Nr; 71.55.Gs 相似文献
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L.J. Sun J. Hu H.Y. He X.P. Wu X.Q. Xu B.X. Lin Z.X. Fu B.C. Pan 《Solid State Communications》2009,149(39-40):1663-1665
Ag–S codoped ZnO thin films have been fabricated on Si substrates by radio frequency (RF) magnetron sputtering using a thermal oxidation method. XRD and SEM measurements showed that the sample has hexagonal wurtzite structure with a preferential (002) orientation and the surface is composed of compact and uniform grains. AgZn–nSO defect complexes were observed in the Ag–S codoped ZnO films by XPS analysis. Low temperature PL spectra showed neutral acceptor bound exciton emission related to AgZn–nSO. The corresponding acceptor ionization energy of 150 meV is much lower than that of monodoped Ag (246 meV), which is favorable for p-type doping of ZnO. 相似文献
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Optical properties of p-type ZnO doped by lithium and nitrogen 总被引:1,自引:0,他引:1
X.H. Wang B. Yao D.Z. Shen B.H. Li Y.M. Lu J.Y. Zhang L.X. Guan 《Solid State Communications》2007,141(11):600-604
A lithium and nitrogen doped p-type ZnO (denoted as ZnO: (Li, N)) film was prepared by RF-magnetron sputtering and post annealing techniques with c-Al2O3 as substrate. Its transmittance was measured to be above 95%. Three dominant emission bands were observed at 3.311, 3.219 and 3.346 eV, respectively, in the 80 K photoluminescence (PL) spectrum of the p-type ZnO:(Li, N), and are attributed to radiative electron transition from conduction band to a LiZn-N complex acceptor level (eFA), radiative recombination of a donor-acceptor pair and recombination of the LiZn-N complex acceptor bound exciton, respectively, based on temperature-dependent and excitation intensity-dependent PL measurement results. The LiZn-N complex acceptor level was estimated to be about 126 meV above the valence band by fitting the eFA data obtained in the temperature-dependent PL spectra. 相似文献
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We performed first-principle total-energy calculations to investigate the mechanism for the realization of high quality p-type ZnO codoped with lithium and nitrogen. We find that the higher hole concentrations measured in the codoped ZnO is related to decreased ionization energy of acceptors and reduction of compensations. The dual acceptor NO-LiZn complex proposed in experiments is unstable. While in the (LiI-NO)-LiZn complex, where acceptor LiZn binds to the passivated (LiI-NO) complex is stable and acts as a single acceptor. The activation energy of this complex is about 60 meV lower than that of LiZn in Li-monodoped ZnO. The formation of inactive (LiI-NO) complexes creates a fully occupied impurity band just above the valence band maximum of ZnO. Thus Li atoms binding to this complex is activated by the electrons from the complex state rather than from the host states, accounting for decreased activation energy. Besides, LiI+ and NO− bind tightly through the Coulomb interaction. Such binding will suppress the amount of compensating donor LiI and limit the compensation for the desired acceptor LiZn. 相似文献
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Tingting Guo Guobo Dong Qiang Chen Xungang Diao Fangyuan Gao 《Journal of Physics and Chemistry of Solids》2014
Based on first-principles calculations, (Sb, N) codoped ZnO are investigated. We find that SbZn–4NO have lower formation energy and can form p-type conduction with smaller hole effective mass. In comparation to monodoping of Sb, SbZn–4NO complex can form better p-type conductivity than SbZn–2VZn, which may be strongly compensated by SbZn defect and result in a decrease of p-type conduction. So we inferred that (Sb, N) codoping in ZnO under O-poor condition should be a realizable candidate of p-type conduction. 相似文献
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Li-N dual-doped p-type ZnO (ZnO:(Li, N)) thin films are prepared by pulsed laser deposition. The optical properties are studied using temperature-dependent photoluminescence. The Lizn-No complex acceptor with an energy 1evel of 138 me V is identified from the free-to-neutral-acceptor (e, A0 ) emission. The Haynes factor is about 0.087 for the Lizn-No complex acceptor, with the acceptor bound-exciton binding energy of 12meV. Another deeper acceptor state located at 248 meV, also identified from the (e, A0) emission, is attributed to zinc vacancy acceptor. The two acceptor states might both contribute to the observed p-type conductivity in ZnO:(Li,N). 相似文献
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The effect of changes in Li content on the structural property of sol-gel Li-doped ZnO films was investigated in this study. The observed changes of the Li incorporation-induced strain along c-axis are closely related to the different ratios between the concentrations of Li interstitials (Lii) and Li substituting for Zn (LiZn) in the films. According to the observed results from X-ray diffraction (XRD) and photoluminescence measurements, we found that the domination of the dissociative mechanism in the Li-doped ZnO films led to transformation from LiZn to Lii, involving the formation of Zn vacancies (VZn). In addition, the interaction between these defects (that is, LiZn, Lii, VZn and oxygen vacancy) and the crystal structure may lead to the abnormal shift of the (0 0 2) diffraction peak position determined from XRD measurements. 相似文献
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Using first-principles calculations based on density functional theory, we investigated systematically the electronic structures and magnetic properties of N monodoping and (Li, N) codoping in ZnO. The results indicate that monodoping of N in ZnO favors a spin-polarized state with a magnetic moment of 0.95 μB per supercell and the magnetic moment mainly comes from the unpaired 2p electrons of N and O atoms. In addition, it was found that monodoping of N in ZnO is a weak ferromagnet and it is the spin-polarized O atoms that mediate the ferromagnetic exchange interaction between the two N atoms. Interestingly, by Li substitutional doping at the cation site (LiZn), the ferromagnetic stability can be increased significantly and the formation energy can be evidently reduced for the defective system. Therefore, we think that the enhancement of ferromagnetic stability should be attributed to the accessorial holes and the lower formation energy induced by LiZn doping. 相似文献
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采用基于密度泛函理论的广义梯度近似平面波赝势方法,探究四种ZnO-Σ7(1230)孪晶界中V_(Zn)-N_O-H复合体的电子结构和p型导电机理.计算结果表明,在ZnO-Σ7(1230)孪晶界中,N掺杂后会与锌空位(V_(Zn))、氢填隙(Hi)等点缺陷结合,进而形成V_(Zn)-N_O-H复合体,并出现在孪晶中的晶格应变集中区.此外,四种孪晶界中孪晶GB7a有利于V_(Zn)-N_O-H离化能降低,从而使其表现出浅受主特征.分析显示特殊的孪晶结构导致了氮替位(N_O)与近邻的O原子间距离缩短,阴离子之间发生相互作用,导致禁带中的空带能级下降,降低了电子跃迁所需能量.这一结果也说明GB7a孪晶界中的V_(Zn)-N_O-H可能成为N掺杂ZnO材料的p型导电的来源之一. 相似文献