共查询到20条相似文献,搜索用时 187 毫秒
1.
建立了electronphononfield(EPF)电子隧穿电导模型,推导了一维无序体系新的交流电导公式.通过计算具有20000—65000个格点的无序体系的交流电导率,分析了交流电导率与温度及外场频率的关系,讨论了无序度对交流电导的影响.计算结果表明,无序体系的交流电导率随外场频率的增加而近似线性的增大;无序体系在低温区出现了负微分电阻特性,电导率随温度的升高而增大,在高温区电导率随温度的升高而减小;无序度对无序体系的交流电导影响明显:在低温区,无序度越小,体系的电导率越大;在高温区,适当增大无序度,
关键词:
无序体系
电子隧穿
跳跃电导 相似文献
2.
3.
用渗银和银胶接触两种方法分别在多晶Nd0.7Sr0.3MnO3陶瓷样品上制作电极,用两线和四线模式对两种接触界面的直、交流特性进行测量.结果发现:渗银电极与陶瓷样品之间具有很好的欧姆接触特性,两线、四线模式下的电阻测量值相近,并且没有电脉冲诱导电阻转变(EPIR)效应;而用银胶接触作电极时,V-I曲线表现出关于原点对称的非线性特征,并出现稳定的室温EPIR效应.两种不同方法制备的电极在交流电场下的输运也有很大差异:渗银电极阻抗
关键词:
界面
接触电阻
EPIR效应
钙钛矿结构锰氧化物 相似文献
4.
研究了用于SiCOH 低介电常数薄膜刻蚀的CHF3气体在1356 MHz/2 MHz,2712 MHz/2 MHz和60 MHz/2 MHz双频电容耦合放电时的等离子体性质.发现2 MHz低频源功率的增大主要导致F基团密度的增大;而高频频率从1356,2712增大到60 MHz,导致CF2基团的密度增大和电极之间F基团密度的轴向空间不均匀性增加.根据电子温度的分布规律及离子能量随高频源频率的变化关系,提出CF2基团的产生主要通过电子-中性气体碰撞,而F基团的产生是离子-中性气体碰撞的结果.
关键词:
双频电容耦合放电
3等离子体')" href="#">CHF3等离子体 相似文献
5.
以Ta,TaN为衬底,采用原子层淀积方法制备高介电常数HfO2介质,比较研究了不同衬底电极对金属-绝缘体-金属(MIM)电容的性能影响.结果表明,采用TaN底电极能够获得较高的电容密度和较小的电容电压系数(VCC),在1MHz下的其电容密度为7.47fF/μm2,VCC为356ppm/V2和493ppm/V,这归因于TaN底电极与HfO2介质之间良好的界面特性.两种电容在3?V时漏电流为5×10-8关键词:
高介电常数
MIM电容
2薄膜')" href="#">HfO2薄膜
电极 相似文献
6.
报道了SiCl4/H2等离子体化学气相沉积方法制备的未掺杂微晶硅薄 膜,在短时间光照或加上直流偏压后其室温暗电导随时间缓慢变化的行为. Raman散射谱结 果表明,薄膜的晶态体积比大于70%. 暗电阻的实验结果显示: 材料具有弱的持久光电导效 应;薄膜的暗电导在外加直流电场的作用下缓慢上升,电场反向后出现暗电导的恢复过程, 而且暗电导变化速度与偏压大小和温度有关. 根据异质结势垒模型,指出外加条件下载流子 的空间分离和重新分布以及材料非均匀性造成的势垒是引起电导
关键词:
微晶硅
电导率
薄膜 相似文献
7.
采用有效哈密顿量和有相互作用的分立势模型,利用格林函数和耦合参量得出了量子点(腔)在有结边电荷积累极化时的线性和二阶非线性交流电导虚部(emittance)的明确表达式.发现在经典情况下,电导虚部和电化学电容都等于经典的几何电容.在非经典情况下,如果发生全反射,电导虚部和电化学电容相等,但两者皆不等于经典的几何电容.在有隧穿的情况下,电导虚部和电化学电容以及经典电容三者都不相等.该结果对于量子器件中的电容测量具有指导作用.
关键词:
格林函数
交流电导
电化学电容 相似文献
8.
用脉冲激光沉积法在(111)Si衬底上成功制备了高度择优取向的Fe3O4薄膜.电阻-温度关系表明Fe3O4薄膜的Verwey转变(TV)约在122 K,低温段(TV)输运特征满足Mott变程跳跃模型,高温段(T>TV)为小极化子输运.激光作用下的光电导实验发现,在整个温区表现为光致电阻率减小,而且低温段的电阻变化率比高温段要大很多.分析认为Fe3O4薄膜的光致电阻率变化主要与激光激发t2g电子的转移有关.
关键词:
3O4薄膜')" href="#">Fe3O4薄膜
小极化子
光诱导特性 相似文献
9.
10.
11.
本文用固相反应烧结制备出Li2Mo2O6多晶材料。经X射线分析、红外光谱和电子顺磁共振谱(EPR)的研究,确定了它的结构是Li2Mo2O4和MoO2两个晶相组成的烧结体。钼离子以四价状态存在于MoO2晶相结构中。采用交流阻抗谱分析了晶界与温度变化的相关性。测得了样品的ln(σ总T)-1/T 曲线是由两段直线和一段曲线所组成;总电导率化能σ27℃=1.36×10-3(Ω·cm)-1,σ115℃=1.49×10-3(Ω·cm)-1,σ300℃=9.71×10-3(Ω·cm)-1,σ370℃=2.42×10-3(Ω·cm)-1;电导活化能E1=0.043eV,E2=0.235eV,E平均=0.76eV。采用维格纳极化电池法测得电子电导率σe,σe27℃=2.240×10-5(Ω·cm)-1,σe300℃=4.476×10-3(Ω·cm)-1。实验证明,室温下材料为固体电解质,300℃附近为良好的离子与电子混合导体。
关键词: 相似文献
12.
本文研究了Lisicon(锗酸锌锂)单晶的Li+离子电导率。发现各结晶学方向电导率之间的关系为σb≤σa≤σc≤σ[110],但各向异性不强。晶体中Li含量对电导率有明显的影响,当Li/Zn比率由6.7变到9.2时,300℃a方向电导率由4.3×10-2Ω-1·cm-1增加到1.25×10-1Ω-1·cm-1,logσT对1/T的曲线显示出三个转变点,分别在~80℃,~140℃和~300℃。电导的激活能分别为0.50—0.58eV(25—80℃),0.92eV(~80—140℃),0.64eV(~140—300℃)和0.36eV(>300℃),极化实验表明单晶的电子电导可以忽略。
关键词: 相似文献
13.
14.
M. Büscher R. Eßer A. Franzen L. v. Horn D. Kopyto H. Ohm H. Seyfarth K. Sistemich H. Müller B. Prietzschk B. Rimarzig C. Schneider C. Schneidereit A. Akindinov M. Chumakov V. Demechin V. Ergakov A. Gerasimov V. Goryachev Y. Kiselev V. Kostromin A. A. Sibirtsev V. Sopov V. Tchernyshev V. Kruglov A. Petrus V. Koptev S. Mikirtychyants 《Zeitschrift für Physik A Hadrons and Nuclei》1996,355(1):93-100
The production ofK + andπ + mesons and protons inpBe collisions atT p=2.9 GeV has been studied at the ITEP proton synchrotron. Ejectiles with a momentum ofp=545 MeV/c were observed under an emission angle ?=17°. The detectors which have been developed for the identification of kaons out of a six orders of magnitude more intense background of pions and protons are described. A cross-section ratio d2σ K +/dΩdp: d2 σ p /dΩdp: d2σ p /dΩdp of (1±0.34):(85±1):(31±1) has been measured. Normalization with existing pion data yields an invariant differential cross sectionE·d3σ K +/d3 p=(3.1±1.2) mbGeV?2c3sr?1 and a total cross section of σtot(pBe)=(3.7±1.5) mb. These cross sections are compared with existing data and theoretical predictions. TheA dependence ofK + production in the few-GeV range is analyzed. 相似文献
15.
NMR in the alkali molecules Na2 and Cs2 is performed by the atom-molecule exchange optical pumping method. The shielding differences σ(Na)?σ(Na2)=(29±16)·10?6 and σ(Cs)?σ(Cs2)=(221±12)·10?6 are obtained. The investigation of the contribution of the valence electron to the magnetic shielding is supported by a NMR experiment in free Cs+ ions, which yields the shielding difference σ(Cs)?σ(Cs+)=(14±12)·10?6. These measurements allow an estimation of the spin rotation interaction constant in these molecules. 相似文献
16.
Fabrication and characterization of 4H—SiC bipolar junction transistor with double base epilayer
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
In this paper we report on a novel structure of a 4H-SiC bipolar junction transistor with a double base epilayer that is continuously grown.The measured dc common-emitter current gain is 16.8 at IC = 28.6 mA(J C = 183.4 A/cm2),and it increases with the collector current density increasing.The specific on-state resistance(Rsp-on) is32.3mΩ·cm 2 and the open-base breakdown voltage reaches 410 V.The emitter N-type specific contact resistance and N + emitter layer sheet resistance are 1.7×10-3 Ω·cm2 and 150 /,respectively. 相似文献
17.
Erik Jacobson 《Zeitschrift für Physik A Hadrons and Nuclei》1972,251(3):214-230
The decay ofrf resonance signals (Δm F =± 1, ΔF=0) in the hfs-states (F=3/2, 5/2) of the 63 P 2-state of199Hg has been observed by means of a sampling method. By comparing the relaxation times to those of the even isotopes, the cross section σ2(F) for the destruction of an alignment in the hfs-states by collisions with ground state Hg-atoms could be measured. The following ratios were obtained: σ2(F=3/2)/σ2=1.04±0.06 and σ2(F=5/2)/σ2=0.90± 0.03. The cross section σ2 for the even isotopes was found to be (2.620±0.265) 10?14cm2. Assuming total decoupling of nuclear spinI and electronic angular momentumJ during the collision, the cross sections for the destruction of an orientation (σ1) and an “octupolarisation” (σ3) could be calculated. For the even isotopes the following ratios were derived: σ1/σ2=0.76 ± 0.07 and σ3/σ2=1.08 ± 0.09. 相似文献
18.
在成功制备具有双钙钛矿结构Sr2Fe1-xCoxMoO6系列样品的基础上,对其结构、输运性质和磁性质进行了系统研究.结果发现,随着Co替代浓度x值的增加,样品的电阻率-温度关系由半金属行为转变为半导体行为,其室温电阻率从3.9×10-5Ω·cm增大到6.0×10-1Ω·cm;样品由亚铁磁体转变成反铁磁体,其磁相变温度TN值也随之下降; Co对Fe的部分替代使其磁电阻效应受到抑制.基于对其电子结构的分析,其磁电阻效应的起源以及Co的元素替代效应也在文中进行了讨论.
关键词:
双钙钛矿结构
2FeMoO6')" href="#">Sr2FeMoO6
磁电阻 相似文献
19.
Jun Li Fan Zhou Hua-Ping Lin Wen-Qing Zhu Jian-Hua Zhang Xue-Yin Jiang Zhi-Lin Zhang 《Current Applied Physics》2012,12(5):1288-1291
We have fabricated indium–gallium–zinc (IGZO) thin film transistor (TFT) using SiOx interlayer modified aluminum oxide (AlOx) film as the gate insulator and investigated their electrical characteristics and bias voltage stress. Compared with IGZO-TFT with AlOx insulator, IGZO-TFT with AlOx/SiOx insulator shows superior performance and better bias stability. The saturation mobility increases from 5.6 cm2/V s to 7.8 cm2/V s, the threshold voltage downshifts from 9.5 V to 3.3 V, and the contact resistance reduces from 132 Ωcm to 91 Ωcm. The performance improvement is attributed to the following reasons: (1) the introduction of SiOx interlayer improves the insulator surface properties and leads to the high quality IGZO film and low trap density of IGZO/insulator interface. (2) The better interface between the channel and S/D electrodes is favorable to reduce the contact resistance of IGZO-TFT. 相似文献