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Positron beam Studies of transients in semiconductors

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Positron beam Studies of transients in semiconductors

第九届全国正电子谱学会议

作者： c.d.beling department of Physics The University of Hong KongPokfulam RoadHong KongP.R.C.

A few years ago our laboratory proposed a novel technique for investigating defects in semiconductors that involved combining conventional positron doppler Broadening Spectroscopy (dBS) with deep Level Transient Spectroscopy (dLTS). This new technique, which was referred to as Positron deep Level Transient Spectroscopy (PdLTS) suffered however from a major drawback, namely that the electric fields established in the sample during the transient by virtue of the ionized shallow donors/acceptors would cause positrons to accelerate into the contact/bulk with too small a fraction being available to trap into defects undergoing ionization. The

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GaN中的缺陷与杂质

物理学进展 2001年第1期21卷 1-11页

作者：许小亮施朝淑 S.Fung c.d.beling 中国科学技术大学物理系合肥230026 香港大学物理系

GaN是一种新型的宽禁带半导体兰色发光与激光材料。GaN中的缺陷和杂质对于材料的电学输运特性和发光性能有着至关重要的影响。本文综述了近年来对于GaN中缺陷和杂质的理论与实验研究。包括对天然缺陷与非特意性掺杂的研究。

关键词： GaN 缺陷杂质深能级离子注入半导体材料电学输运特性发光性能

Theoretical Simulation of Positron Annihilation

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Theoretical Simulation of Positron Annihilation

第九届全国正电子谱学会议

作者： c.d.beling S.Fung department of Physics the University of Hong Kong Pokfulam Road Hong Kong (SAR) P. R.C.

An implement of theoretical simulation of positron annihilation in solid is shown. It is based on two components dFT (density functional theory). The electron component is performed by the method, FLAPW (full-potential linearized augmented plane wave), which is one of most accurate methods, full-potential and all-electrons, on the commercial program WIEN2K. With the help of zero density approximation of

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Semi-insulating GaAs studies at different temperatures by positron spectroscopy

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Semi-insulating GaAs studies at different temperatures by po...

第九届全国正电子谱学会议

作者： F.Nahid c.d.beling S.Fung department of Physics the University of Hong KongPokfulam RoadHong Kong(SAR)P.R.C.

Positron Annihilation Lifetime Spectroscopy (PALS) is a powerful technique to measure the open volume (neutral or negative) type defect in different materials which can give the information of the defect size distribution. The temperature variable PALS system has been set up at HKU for study the positron trapping at defect level at low temperature. For the first trying, We have performed positron lifetime

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Influence of Fe doping concentration on Some Properties of Semi-Insulating InP

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Journal of Semiconductors 2002年第10期23卷 1041-1045页

作者：赵有文罗以琳冯汉源 c.d.beling 林兰英中国科学院半导体研究所材料科学中心北京100083 汕头大学物理系汕头515000 香港大学物理系

Properties of Fe-doped semi-insulating (SI) InP with different iron concentrations are studied by using Hall effect,current-voltage ( I-V ),photoluminescence spectroscopy (PL) and photocurrent spectroscopy(Pc)measurements. I-V characteristics of SI InP strongly depend on Fe doping *** doping concentration also influences optical properties and defective formation in as-grown SI ***-gap narrowing phenomenon and defects in Fe doped SI InP are studied using PL and Pc.

关键词： InP semi-insulation defects

Positron Annihilation Lifetime Spectroscopy study using non-negativity Huber deconvolution

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Positron Annihilation Lifetime Spectroscopy study using non-...

第九届全国正电子谱学会议

作者： c.d.beling S.Fung K.P.Ng department of Physics the University of Hong Kong Pokfulam Road Hong Kong (SAR) P. R.C. department of Mathematics the University of Hong Kong Pokfulam Road Hong Kong (SAR)P.R.C.

In the positron annihilation lifetime experiment, the data collected is superimposition of exponential decay spectra, which is convoluted with the IRF (Instrumental Resolution Function) that can be approximated as one or several Gaussians plus background noise. We are planning to use the non-negativity 1-d Huber deconvolution to solve the inverse problem to find the lifetimes and intensities

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Investigation of Residual donor defects in Undopedan d Fe-doped LEc InP

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Journal of Semiconductors 2002年第5期23卷 455-458页

作者：赵有文孙聂枫冯汉源 c.d.beling 孙同年林兰英中国科学院半导体研究所材料中心北京100083 河北半导体研究所石家庄050051 香港大学物理系

The free electron concentration of as-grown liquid encapsulated czochralski (LE c) InP measured by Hall effect is much higher than the concentration of net dono r impurity determined by glow discharge mass *** of the existe nce of a native donor hydrogen-indium vacancy complex in LEc undoped and Fe-do ped InP materials can be obseved with infrared absorption *** concentra tion increase of the donor complex correlates with the increase of ionized deep acceptor iron impurity Fe concentration in Fe-doped semi-insulating (S I) *** results indicate that the hydrogen-indium vacancy complex is an im portant donor defect in as-grown LEc InP,and that it has significant influence on the compensation in Fe-doped SI InP

关键词： indium phosphide semi-insulating donor defect

Preliminary Studies on a Variable Energy Positron Annihilation Lifetime Spectroscopy(VE-PALS) System

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Preliminary Studies on a Variable Energy Positron Annihilati...

第九届全国正电子谱学会议

作者： P.Y.Kwan c.K.cheung c.d.beling S.Fung department of Physics The University of Hong KongPokfulam RoadHong KongP.R.C.

There are many advantages to being able to perform PALS (Positron Annihilation Lifetime Spectroscopy) using a variable energy positron beam, the most obvious being the easy identification of different defect types. The difficulty in conducting VE (Variable Energy) PALS studies lies in the fact that a "start" signal is required to signal the entry of the positron into the target. Two methods have been used to overcome this problem, namely the bunching technique which employs RF cavities and choppers, and secondly the use of secondary electrons emitted from the target. The latter technique

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deconvolution Study by the Lucy-Richardson Algorithm on cdBARS 2-d spectra compared with other methods

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Deconvolution Study by the Lucy-Richardson Algorithm on CDBA...

第九届全国正电子谱学会议

作者： c.K.cheung c.d.beling S.Fung K.P. Ng department of Physics The University of Hong KongPokfulam RoadHong KongP.R.C. department of Mathematics The University of Hong KongPokfulam RoadHong KongP.R.C.

It is very difficult to make differences between hardware instrumentation and software instrumentation since through dSP (digital Signal Processing) technology many deconvolution mathematical algorithms can be included into the instrumentation by Ic techniques to improve the instruments’ resolution. However, digital signal processing can always show some strange results due to noise sensitivity of inverse procedure, singular value problem, divergence problems, ring effects which make the deconvolution results difficult to explain. Further more, the limitation of the

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