Hg_(1-x)Mn_xTe:红外探测器材料的一种新的侯选者

美国印第安纳州普杜大学物理系J.K.Furdyna在《SPIE》Vol.409(1983)上介绍一种新型材料Hg_(1-x)Mn_xTe,并将它与大家熟知并公认为目前最有前途的材料Hg_(1-x)Cd_xTe相比较。Hg_(1-x)Mn_xTe与Hg_(1-x)Cd_xTe这两种半导体材料有许多相似之处。在材料结构和晶体特性方面,Hg_(1-x)Mn_xTe也是一种优质的闪锌矿结构晶体,生长方法亦类似,只是Hg_(1-x)Mn_xTe的     

半磁半导体Cd_(1-x)Fe_xTe的光学和磁性质的研究

用透射光谱法报道和讨论了组份x=0.03和x=0.06的Cd_(1-x)Fe_xTe单晶样品的光吸收,同时用提拉法在温度1.5～30K、磁场强度直到7T范围内测量了磁化强度与组份、温度和磁场强度的变化规律。结果表明,随着x组份的增加,Cd_(1-x)Fe_xTe的能隙移向长波(低能)方向。根据分子场理论,采用类布里渊函数,对磁化强度实验结果进行了拟合和分析。在本文的x值范围内,理论与实验符合得很好,证实了铁离子间存在反铁磁的交换耦合。     

Cd_(1-x)Mn_xTe基本吸收边的研究

报道了用透射法在10～300K温度范围内测量不同组分(x=0.007、0.20、0.30和0.45)Cd_(1-x)Mn_xTe的基本吸收边,结果表明,能隙随温度线性变化,能隙的温度系数为负并显著地随Cd_(1-x)Mn_xTe混晶的组分变化。     

窄禁带半导体的自由载流子吸收

从理论和实验上研究了77K和300K温度下,本征型半导体InSb,Hg_(1-x)Cd_xTe,Hg_(1-x)Mn_xTe和高掺杂Hg_(1-x)Cd_xTe在2.5～50μm波段范围内的自由载流子吸收,结果表明:对于所研究的三种本征型样品,均是极性光学声子散射起主要作用,对于InSb还应考虑声学声子和电离杂质散射。对有缺陷的Hg_(1-x)Mn_xTe样品,理论计算的自由载流子吸收系数与实验值不一致,表明存在附加的散射机制,对高掺杂Hg_(1-x)Cd_xTe的研究证实了这一假设。还讨论了非弹性电子-声子散射机制的起因,估算了特性参数。     

由电容温度关系分析HgCdTe深能级特性

本文报道 Hg Cd Te深能级的实验研究,对合金组分 x=0.21-0.28的Hg_(1-x)CdxTe光二极管作了测量.用P-N结电容随温度变化关系分析了陷阱激活能和密度.     

用红外光吸收法测定Hg_(1-x)Cd_xTe组分

在室温下测量了组分x=0.170～0.443的Hg_(1-x)Cd_xTe薄样品的本征吸收光谱,并采用参考文献[4][5]中的方法确定其禁带宽度,发现与禁带宽度相当的能量处的吸收系数为α(E_g,300K)=500 5600x。把该式作为用红外光吸收法测定Hg_(1-x)Cd_xTe组分的工作曲线,先测出未知组分的Hg_(1-x)Cd_xTe厚样品的吸收边,并延长到α(E_g,300K)处,得到E_g(300K)后,即可求得待测组分:     

Hg1—xCdxTe组分与红外透射光谱的关系

根据Hg_(1-x)Cd_xTe吸收系数与光子能量之间的指数关系和文献[3]的实验结果,推导出由透射光谱求组分x的表达式。该式的使用不受测量温度和晶片厚度的限制。实验结果表明,用本文给出的表达式求出的x值与用Finkman法和密度法得到的x值是一致的,但比Finkman法简便。     

用光截止法测量Hg_(1-x)Cd_xTe的横向组分均匀性

本文以相当可靠的黑体辐射公式为基础,利用Hg_(1-x)Cd_xTe样品本身的光截止特性测量样品的截止波长,再用E_g-x经验公式求出样品的组分(?)对样品进行二维扫描,获得了Hg_(1-x)Cd_xTe样品横向组分的面分布。测得的组分均方根偏差与电子探针的测量结果符合得很好。     

用光截止法测量Hg_(1-x)Cd_xTe的横向组分均匀性

本文提出一种测量Hg_(1-x)Cd_xTe横向组分均匀性的简便方法。该方法以相当可靠的黑体辐射公式为基础,利用Hg_(1-x)Cd_xTe样品本身的光截止特性,测量样品的截止波长,再用E_(?)-X经验公式求出样品的组分X。通过对样品的二维扫描,可求得Hg_(1-x)Cd_xTe横向组分的面分布。透光因子的定义     

用红外光吸收法测定Hg_(1-x)Cd_xTe的组分

本文用测量本征吸收光谱的方法,确定Hg_(1-x)Cd_xTe的禁带宽度Eg值,再根据Eg与x的关系来确定x值。在Hg_(1-x)Cd_xTe的本征吸收光谱上,Eg能量值出现在陡峭的指数吸收边和平坦的本征吸收带交界区域。利用本征吸收光谱确定Eg,需要对Hg_(1-x)Cd_xTe薄样品进行测量,样品厚度一般为10μm左右。我们用PE983红外分光光度计在室温下测量了七个已知组份的     

A novel SOI MOSFET electrostatic field sensor

A novel low temperature solid state electric field sensor is demonstrated as a promising sensor. The sensor is a type of constant voltage Wheatstone bridge whose resistors are four direct gate SOI MOSFET devices. It is demonstrated in theory that the output voltage signal is proportional to the electric field E, the temperature drift is about zero when the temperature is in the range from 200 to 400 K, and the doping concentration is in the range from 1×1014 to 1 × 1016 cm-3. The experiment results indicate that the resolution of the sensor is about 3.27 mV for a 1000 V/m electric field at 300 K, and the voltage drift by an amount is about 47 V/m field signal when the degree temperature is in the range from 300 to 370 K, which is much smaller than the current drift of a single MOSFET which is about 10000 V/m field signal.     

一种新型MOSFET静电场传感器

本文提出了一种非常有发展前途的低温漂固态电场传感器。此传感器是一种恒压惠斯顿电桥,它的电阻是由四个直接栅极SOI MOSFET器件。理论上证明这种传感器的输出信号电压与测量电场成正比,温度漂移等于零。实验结果表明,在300K温度下,传感器的分辨率为3.27 mV/KV/m,大气环境下的温度漂移相当于47V/m的电场,其远小于大气温度下相当于10,000V/m的电流漂移。     

The effects of temperature on epitaxial InP transferred electron devices

The performance of Indium Phosphide microwave oscillators is examined over the temperature range 110-470 K. The threshold field of the devices is shown to vary from 7 kV.cm^-1at 110 K up to 10 kV. cm^-1at 470 K, with a value of 8 kV.cm^-1at room temperature. The results indicate little falloff in the operating efficiency of the oscillators between room temperature and 470 K. The operating frequency bands are shown to fall with increasing temperature with the frequency for maximum power changing by about 18 percent over the range 290-470 K.     

Temperature and magnetic-field dependences of the thermoelectric power of electronic indium antimonide

The thermoelectric power of electronic indium antimonide with n = 2 × 10¹⁴ cm^?3 in a transverse magnetic field as high as 7 kOe is studied in the temperature range from 4.8 to 120 K. The thermoelectric power is found to be independent of field at a temperature close to 56 K.     

Large,Temperature‐Tunable Low‐Field Magnetoresistance in La0.7Sr0.3MnO3:NiO Nanocomposite Films Modulated by Microstructures

Magnetic properties and low‐field magnetoresistance (LFMR) in La_0.7Sr_0.3MnO₃ (LSMO):NiO nanocomposite films grown on SrTiO₃ (001) substrates, which are shown to be tunable with different microstructures, are investigated. The LSMO:NiO nanocomposite films with NiO volume ratio of 50% have a checkerboard‐like structure and show a large LFMR in a temperature range from 200 to 300 K (≈17% at 250 K with a magnetic field of 1 T). As the NiO volume ratio is increased to 70%, a nano‐columnar structure formed in the films. Their LFMR is significantly enhanced at a wide temperature range of 10–210 K. The highest value of LFMR with 41% is achieved at 10 K in a magnetic field of 1 T. The enhanced LFMR can be considered to result from the electron scattering at the ferromagnetic LSMO/NiO interfaces and magnetic tunnel junctions (MTJs) of LSMO/NiO/LSMO at the nanometer scale. These results demonstrate that large and tunable LFMR from low temperature to room temperature can be realized by controlling the microstructures in the epitaxial La_0.7Sr_0.3MnO₃:NiO nano­composite thin films, which will be expected to be applied in the devices using for a wide temperature range.     

Impedance and noise in the channel of a GaAs Schottky-gate field-effect transistor

The behaviour of the impedance and noise of the channel of a GaAs Schottky-gate field effect transistor is experimentally analyzed in the temperature range 77–300K and in the frequency range of 150 to 900 MHz. The channel of the transistor (source and gate being short circuited) shows a thermal noise level in good agreement with van der Ziel's theory. At 77K, the observed excess of the noise temperature is attributed to an effect of hot carriers.     

Millimeter and Submillimeter Wave ESR System: Using 30 T Pulsed Magnetic Field

New systems for millimeter and submillimeter wave ESR have been developed in Kobe University. In the previous system the pulsed magnetic field was limited up to 17 T in the temperature range from 1.8 to 86 K. Using the new systems, we can measure in the field range up to 30 T in the temperature range from 1.8 K to 4.2 K and from 18 K to room temperature. The resolution of the magnetic field has been also improved in the new ESR system. The details of our new ESR systems are presented. In addition, the measurements of Yb₂Cu₂O₅ using these new systems are presented.

     

A temperature-dependent MOSFET inversion layer carrier mobilitymodel for device and circuit simulation

A new semi-empirical model for electron and hole mobilities in MOSFET inversion layers is proposed. For the first time, the magnitude of the key parameter η, which defines the effective transverse field, is found to be a continuous function of temperature for both electrons and holes. The effective transverse field dependences of the universal mobility curves are observed to differ between the electrons and holes, particularly at low temperatures. The proposed model is verified by comparison of experimental data and simulated MOSFET I-V characteristics over a temperature range from 77 K to 313 K     

准二维天然超晶格物质Mo_4O_(11)的输运现象

报告了准二维天然超晶格物质η-Mo4O11（在105K和35K呈现两次电荷密度波转变）在温度4．2－300K，脉冲磁场40T范围内的输运性质。动态和静态的温度特性均在转变温度附近呈现出明显异常。对其高压下的特性也作了报道。     

Temperature-dependent hole and electron mobility models for CMOScircuit simulation

Semi-empirical hole and electron mobility models with temperature dependence have been proposed for circuit simulation as well as for process characterization. These models are based on the universal dependence of low field mobility on the effective transverse field and cover a wide range of oxide thickness as well as of temperature. The accuracy of our models is justified by comparing them with experimental work reported in the literature as well as that obtained in our laboratory. They are accurate and physical enough to be suited for the circuit simulation of modern VLSI CMOS circuits with gate oxide thickness less then 400 Å in the temperature range of 250-400 K