渡越时间方法测量聚合物材料的载流子迁移率

介绍了渡越时间方法的测量原理,讨论了激发光源的波长、单脉冲能量、脉冲宽度以及测量电路的积分时间常数、聚合物材料的光生载流子率、样品的制备、探测器的选取等测试条件对聚合物材料载流子迁移率测量结果的影响。实验表明,利用渡越时间方法测量聚合物材料载流子迁移率,只有严格选取合适的测量条件,才可获得准确、可靠的测试结果。     

载流子迁移率测量的光电方法

本文评述了载流子迁移率测量的各种方法,着重介绍了光电测量的渡越时间(TOF)方法,并对几种新的含偶氮基、硝基及咔唑基的光电功能材料进行了测量,给出了迁移率的测量结果.     

载流子迁移率测量方法研究

给出了载流子迁移率的各种测量方法,渡越时间（TOP）法、霍尔效应法、电压衰减法、辐射诱发导电率（SIC）法、表面波传输法、外加电场极性反转法和电流-电压特性法,并给出了这些测量方法的使用范围。     

有机光电材料载流子迁移率测量方法

有机光电材料大致可分为小分子或低聚物和聚合物两类.载流子迁移率是衡量有机光电材料导电性能的重要参数,直接关系到材料对电荷的传输能力.因此,测量材料的载流子迁移率是研究有机光电材料的基本工作之一.通过对几种不同测试方法的总结与分析,报道了几种载流子迁移率测试技术,并指出各种测试方法的应用原理及适用的测试范围,对采用合理的...     

载流子迁移率测量方法总结

给出了载流子迁移率的各种测量方法,渡越时间（TOP）法、霍尔效应法、电压衰减法、辐射诱发导电率（SIC）法、表面波传输法、外加电场极性反转法和电流—电压特性法,并给出了这些测量方法的使用范围。     

载流子迁移测量的光电方法

本文评述了载流子迁移率测量的各种方法,着重介绍了光电测量的渡越时间（TOF）方法,并对几种新的含偶氮基,硝基及咔唑基的光电功能材料进行了测量,给出了迁移率的测量结果。     

SiGe层中载流子迁移率研究简况

近些年来的研究结果认为,用Si_(1-x)Ge_x伪晶作成的异质结晶体管是采用硅工艺制作的高速高频器件的最大竞争对手。它的发展速度很快,在很短的时间内就从实验室内的珍品发展成为以硅工艺为基础的速度最快的双极晶体管,不仅设计制成了n-p-n和p-n-p管,而且制成了Si_(1-x)Ge_x伪晶异质结晶体管(PHBT)的集成电路,并获得满意的结果。采用二维漂移扩散(DD)模拟和一维流体学模拟(HD)来分析这类晶体管的高频性能,证明它们的f_r为70GHz左右。     

半导体器件中载流子迁移率的研究

分析了器件中载流子迁移率的基本理论及其受温度、掺杂浓度、栅极电压以及漏极电压的影响,并总结了测量器件中载流子迁移率的几种常用的方法。     

共轭聚合物中载流子迁移率的变温飞行时间检测

载流子迁移率是标定共轭聚合物光电器件性能的重要参数,在数值上其大小远小于传统半导体材料,所以常常用飞行时间方法来测量。利用自行搭建的变温飞行时间检测系统,能够准确地测量聚合物中载流子的迁移率。从原理和实践上,讨论了影响检测结果的限制因素和关键参数,其中包括光生载流子数量、薄膜样品厚度、激发光脉冲宽度、检测外电路的响应时间、载流子在电介质中的弛豫时间和对放大器探测器频率的限制等。只有选取恰当的实验参数才能够获得准确可靠的检测结果。     

基于PC机材料力学微应变自动检测方法研究

材料力学微应变测量实验中，试件在较小负荷作用下所产生的应变信号十分微弱，而各种噪声较被测应变信号强很多倍，因此在信号检测时要设法提高信号的信噪比。实验证明常规的信号检测方法不能够有效地检测出有用信号，这就要求采用微弱信号检测的方法来对被测信号进行处理以实现微弱应变信号的有效检测。     

Accurate measurement of composition, carrier concentration, and photoconductive lifetime in Hg1−xCdxTe grown by molecular beam epitaxy

Variable magnetic field Hall and transient photoconductance lifetime measurements were performed on a series of undoped, In-doped, and As-doped HgCdTe samples grown by molecular beam epitaxy and metalorganic chemical vapor deposition. Temperature variation and, in the case of Hall, magnetic-field variation are needed to give a more complete picture of the mechanisms that control lifetimes in HgCdTe samples. Recent predictions of recombination lifetimes from full band structure calculations were compared to experimental lifetimes at various doping levels at long-wave infrared (LWIR) and mid-wave infrared (MWIR) compositions. For n-type material, lifetimes from low doping levels fall well below the predictions, implying that Shockley-Read-Hall (SRH) recombination is still dominant. MWIR samples have a lifetime that increases somewhat with carrier concentration, suggesting that In doping passivates the SRH defects for that composition. Lifetimes in p-type MWIR material appear to be well-explained by recent theoretical calculations. In p-type material, trapping states may be introduced during the incorporation and activation of As, since some samples with unusually long lifetimes had a distinctly different type of temperature dependence.     

Simultaneous measurement of carrier density and mobility of organic semiconductors using capacitance techniques

We present a method to measure both the majority carrier density and mobility in organic semiconductors from the voltage and frequency dependence of capacitance (C–V–f). Poly(3-hexylthiophene) (P3HT) is used as the prototypical material. The carrier density, and its spatial distribution in a planar device structure, is obtained from a subset of the C–V–f data by conventional capacitance–voltage analysis. We show that the validity of the carrier density extraction depends critically on the measurement frequency. Namely, one should make sure that the measurement frequency is lower than the modified dielectric relaxation frequency, which is characteristically low in organic semiconductors due to their low carrier mobility. Our method further exploits the voltage dependence of the modified dielectric relaxation frequency to measure the conductivity and carrier mobility. This mobility extraction method requires no complex fitting or simulation. Nor does it assume any particular dispersive model of mobility a priori. The carrier density, mobility, and conductivity of P3HT all increase with temperature from 250 to 300 K. The activation energies of mobility and conductivity are 0.15 ± 0.01 and 0.24 ± 0.03 eV, respectively.     

空间载波相移法用于全息CT测量气体温度场

为了能从干涉图像中快速识别相位,将空间载波相移法用于实时全息检测,以电热丝周围的气体为研究对象,采用单次曝光法作了实时全息实验,获得两种干涉图像,结合全息CT技术,均得到了待测气体的温度场.研究结果经比较表明,该方法在实时全息干涉测量中,不但可行,而且准确度高,便于实际应用.     

Modeling the behavior of charge carrier mobility with temperature in thin-film polymeric transistors

In this paper we study the dependence of charge carrier mobility with temperature in polymeric TFTs, PTFTs, using an expression previously derived by us, which has the advantage with respect to previous expressions, that most model parameters represent physical device parameters. Upper gate PTFTs fabricated with polymethyl methacrylate, PMMA, on poly(3-hexyl thiophene), P3HT, and with PMMA on poly(9,9-dioctylfluorene-co-bithiophene), F8T2, working in the temperature range between 300 K and 370 K were used in this study. Each model parameter was extracted at each temperature to determine its variation with T, observing that the bias enhancement parameter for mobility varies much slower than expected, if the characteristic temperature of the distribution of states DOS is considered constant. In this work, this behavior, which has been noticed but not explained before, is analyzed and interpreted, concluding that it has to be considered to represent correctly the behavior of mobility in the normal temperature operating range of PTFTs. Comparison of experimental and calculated data demonstrates the good agreement obtained, showing an Arrhenius-type dependence of the charge carrier mobility with an activation energy in the order of 70 meV and 120 meV for P3HT and F8T2 PTFTs, respectively.     

Electrodeless measurement method of conduction type based on the free carrier absorption effect in CdZnTe

In this paper, we review theoretical and experimental studies on the infrared attenuation spectrum between 400 and 4000 cm⁻¹, which is principally due to the free carrier absorption (FCA). The free carrier absorption is possible by means of inter-conduction band transitions which occur in n-CdZnTe, or by means of inter-valence band transitions which occur in p-CdZnTe. Based on the power law fit results of absorption spectra determined by FCA characteristics, we present an optical measurement technique, which can help us to determine the conduction type of CdZnTe in another way.     

微弱信号检测技术综述

对微弱信号的定义和微弱信号的应用范围进行了概述,并且对当前微弱信号的研究背景做了阐述,重点比较了目前在微弱信号检测技术中应用的方法,最后总结各个方法的特点.