Screening Effects in High Resistivity CdTe for X-ray and Gamma Ray Detectors

The possibility to estimate an upper limit of concentrations of defects forming deep levels in high-resistivity CdTe is discussed based on evaluation of room-temperature photocurrent spectra. A model explaining the shift of the maximum of photocurrent with the applied electric field as a consequence of screening effects caused by space charge accumulated on deep levels is presented. Theoretical calculations show that a maximum concentration of deep levels leading to the observed shift of the photocurrent maximum is less than ∼10¹³ cm⁻³ for typical capture cross sections of electrons and holes. This result supports the models assuming formation of a high-resistivity state with a minimum deep level doping.     

Nitrogen ion irradiation effect on enhancing photocatalytic performance of CdTe/ZnO heterostructures

To deal with the increasingly deteriorating environment problems, more and more harsh requirements are put forward for photocatalysis application. Building semiconductor heterostructures has been proven to be an efficient way to enhance photocatalytic performance. A kind of CdTe/ZnO heterostructures were synthesized by a hydrothermal and successive ionic layer absorption and reaction (SILAR) method and achieved obviously efficient photocatalytic performance. Moreover, after the N ion irradiation treatment, the photocatalytic activity was further enhanced, which can be ascribed to the introduction of oxygen vacancy defects. The photocatalytic performance enhancement mechanism by coupling constructing heterostructures and ion irradiation are further studied to give us an overall understanding on ZnO nanowires.     

CdTe量子点免疫层析试纸条检测克伦特罗

以巯基乙酸作为稳定剂,利用水热反应制备了水溶性的高荧光CdTe量子点,量子产率为54.961%。研究了该量子点在1-（3-二甲氨基丙基）-3-乙基碳二亚胺盐酸盐和N-羟基丁二酰亚胺的作用下与抗克伦特罗抗体的共价连接。结果表明：该量子点与克伦特罗抗体连接后体系的荧光强度和吸光度均增强,且峰位均未发生明显移动,F/P值为4.20。将该偶联反应物CdTe-Anti CLE pAb作为荧光标记物,组装出一种用于检测克伦特罗的荧光免疫试纸条,最低检测限达0.5 μg/L,与酶联免疫吸附法进行对比,该试纸条能够实现对克伦特罗的快速检测。     

碲锌镉探测器对低能X射线的探测

介绍了碲锌镉探测器对低能X射线的探测,并在不同温度下测试了其性能变化,包括电子学噪声,能量分辨率和漏电流的变化.同时研制了低噪、性能稳定的厚膜电路用于单路信号的读出,对241Am的60keV能量峰的能量分辨率达到了4%.     

<Emphasis Type="Italic">In Situ</Emphasis> Spectroscopic Ellipsometry of Rough Surfaces: Application to CdTe(211)B/Ge(211) Grown by Molecular-Beam Epitaxy

The surface morphology of the B-face of (211) cadmium telluride on germanium (211) is investigated by atomic force microscopy (AFM) and generalized ellipsometry (GE). It is apparent that one can obtain roughnesses on the order of two monolayers or less by manipulating the growth conditions. GE confirms that the surfaces are anisotropic. A model based on the Bruggeman effective-medium approximation is used to fit the data and yields values of the roughness that are in good agreement with those found by AFM. In situ data taken during growth are analyzed and a model for them is also proposed to analyze the formation of roughness and its evolution.     

Topography and Dislocations in (112)B HgCdTe/CdTe/Si

Scanning electron microscopy (SEM), atomic force microscopy (AFM), and x-ray diffraction (XRD) measurements all indicate an approximate factor of ten increase in the Everson etch pit density (EPD) over standard Nomarski microscopy Everson EPD determination. A new (112)B CdTe/Si EPD etch has also been demonstrated which reduces the surface roughness of the etched epilayer and makes etch pit density determination less problematic.     

CdTe纳米微粒荧光复合薄膜的制备与表征

半导体纳米晶（QDs）是一种三维团簇．它由有限数目的原子组成稳定的尺寸在2～20nm之间的微粒．三个维度尺寸均在纳米量级．与传统的有机荧光分子相比．量子点具有许多特殊的光学性能：具有激发光谱单一、荧光谱线窄、发光效率高、发光颜色可调、可用同一波长的光激发不同的量子点、可进行多色联合标记等．纳米晶的这些优良性质使其在多元分析、多色成像、     

Analysis of governing factors for photovoltaic loss mechanism of n‐CdS/p‐CdTe heterojunction via multi‐way data decomposition

An analytical framework for identifying key factors of the degradation of photovoltaic efficiency over time is presented. We demonstrate that, in many photovoltaic experimental settings, reliability data sets are easily cast in a multi‐ or N‐way format. We adopt a statistical technique, N‐way partial least squares, that generates a multi‐linear model using all of the data simultaneously. With this approach, we are able to model variables of interest such as cell efficiency while representing the data in a lower‐dimensional space in which salient features are more easily identified. We illustrate our approach with reliability data for CdS/CdTe heterojunction solar cell devices. Even with the inclusion of a noisy parameter such as the net acceptor density, and with a relatively small number of devices, we automatically identify key factors that are highly related to performance degradation. In particular, the conductance at the back contact is related to short stress‐time degradation (0–300 h), whereas the net acceptor density near the junction (at +0.08 V DC bias) is correlated with more gradual, long stress‐time degradation (300–1000 h). These notable degradation modes are explained with respect to our processing conditions and Cu‐diffusion in the cells. Copyright © 2013 John Wiley & Sons, Ltd.     

A system dynamics model of tellurium availability for CdTe PV

The routine availability of key component materials has been highlighted as a potential constraint to both extensive deployment and reduction in production costs of thin‐film photovoltaic (PV) technologies. This paper examines the effect of material availability on the maximum potential growth of thin‐film PV by 2050 using the case of tellurium (Te) in cadmium telluride (CdTe) PV, currently the dominating thin‐film technology with the lowest manufacturing cost. The use of system dynamics (SD) modelling allows for a dynamic treatment of key Te supply features and prospects for reductions in PV demand via material efficiency improvements, as well as greater transparency and a better understanding of future recycling potential. The model's projections for maximum Te‐constrained CdTe PV growth by 2050 are shown to be higher than a number of previous studies using static assumptions—suggesting that a dynamic treatment of the resource constraints for CdTe inherently improves the outlook for future deployment of this technology. In addition, the sensitivity analysis highlights certain complex correlations between the maximum potential CdTe growth by 2050 and the rated lifetime of PV modules as well as the reported size of global Te resources. The highest observed sensitivities are to the recovery rate of Te from copper anode slimes, the active layer thickness, the module efficiency and the utilisation rate of Te during manufacturing, all of which are highlighted as topics for further research. Copyright © 2013 John Wiley & Sons, Ltd.     

Back contact formation in thin cadmium telluride solar cells

We present a model describing the undesired roll-over which is a well-known phenomenon in the current-voltage characteristics of CdTe solar cells. Therein, the roll-over is ascribed to a Schottky barrier at the back contact which is effective as a reverse diode. The formation of this barrier is investigated depending on the CdTe absorber thickness as well as on the employed back contact metal. Computer simulations of the energy band diagram reveal that the back contact barrier can be reduced and even eliminated for sufficiently thin absorbers. The reason is the spatial overlap between the space-charge regions of the p-n heterojunction with the one of the back contact. This behaviour correlates with experimental current-voltage data of solar cells with a simple gold back contact. In the latter, the roll-over is considerable for absorbers with 3 to 5 μm thickness, diminishes when the absorber thickness is reduced and finally vanishes when the absorber thickness is approximately 1 μm. The investigations show that thickness reduction can be employed in order to suppress the roll-over phenomenon in CdTe solar cells.