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Article
The Fundamentals of Plasma-Assisted CVD Technique Employed in Thin Films Production

Author: O.A. Hamadi
Journal: Iraqi Journal of Applied Physics Letters الرسائل العراقية في الفيزياء التطبيقية ISSN: 1999656X Year: 2008 Volume: 1 Issue: 2 Pages: 3-8
Publisher: iraqi society for alternative and renewable energy sources and techniques الجمعية العراقية لمصادر وتقنيات الطاقة البديلة والمستجدة

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Abstract

This paper reviews the physical and chemical principles of plasma-assisted chemical vapor deposition (CVD) technique for thin films. We focus on the integration, process, and reliability requirements for dielectric films used for isolation, passivation, barrier, and antireflective-coating applications in ultra-large-scale integrated (ULSI) semiconductor circuits.


Article
Profiling of Antimony Diffusivity in Silicon Substrates using Laser- Induced Diffusion Technique

Author: O.A. Hamadi
Journal: Iraqi Journal of Applied Physics Letters الرسائل العراقية في الفيزياء التطبيقية ISSN: 1999656X Year: 2010 Volume: 3 Issue: 1 Pages: 23-26
Publisher: iraqi society for alternative and renewable energy sources and techniques الجمعية العراقية لمصادر وتقنيات الطاقة البديلة والمستجدة

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Abstract

In this work, profiles of laser-induced diffusion of antimony in silicon were presented. These profiles were considered to attempt enhancing of the silicon-based devices. This enhancement is attributed to the increasing achieved in the diffusion length within a certain layer of the active region in the device. Laser-induced diffusion is a perfect technique for improving the characteristics of electronic devices since it is flexible, contactless, clean and well controlled.


Article
HAZ Extent Analysis in Fiber-Reinforced Plastic Grooving by Laser

Author: O.A. Hamadi
Journal: Iraqi Journal of Applied Physics المجلة العراقية للفيزياء التطبيقية ISSN: 18132065 23091673 Year: 2005 Volume: 1 Issue: 1 Pages: 1-7
Publisher: iraqi society for alternative and renewable energy sources and techniques الجمعية العراقية لمصادر وتقنيات الطاقة البديلة والمستجدة

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Abstract

In this investigation, the anisotropic extent of HAZ in laser grooving of fiber-reinforced plastic was studied by constructing an analytical model then comparing results obtained with the experimental. A principle of three main components of anisotropic thermal conductivity was considered, and then the equation governing thermal conduction process was transformed to a form similar to that of isotropic material. An analysis, based on a three-dimensional anisotropic thermal conductivity and a moving heat source, was presented to predict HAZ extent in laser grooving of fiber-reinforced plastic. This analysis included prediction of HAZ extent when grooving is parallel to the principal axes and when it is off-axes. The HAZ extent was determined depending on temperature difference relative to matrix combustion or char temperature. With respect to survey of previous works, this investigation is a novel attempt to analyze the extent of HAZ in FRP grooving by a CW CO2 laser.


Article
Effect of Annealing on the Electrical Characteristics of CdO-Si Heterostructure Produced by Plasma-Induced Bonding Technique

Author: O.A. Hamadi
Journal: Iraqi Journal of Applied Physics المجلة العراقية للفيزياء التطبيقية ISSN: 18132065 23091673 Year: 2008 Volume: 4 Issue: 3 Pages: 33-36
Publisher: iraqi society for alternative and renewable energy sources and techniques الجمعية العراقية لمصادر وتقنيات الطاقة البديلة والمستجدة

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Abstract

In this work, the effect of annealing on the electrical characteristics of the CdO-Si heterojunction produced by plasma-induced bonding technique was studied. The heterojunction was consisting of n-type CdO on a p-type silicon substrate. Results showed reasonable improvement in the electrical characteristics of this heterojunction within a range of annealing temperatures, above which the heterojunction showed degradation in its characteristics. This work produces CdO-Si of much better characteristics than same heterojunctions produced by thermal evaporation technique.


Article
Modeling of the Preheating Effect on Keyhole Laser Welding Efficiency

Authors: K.S. Khashan --- O.A. Hamadi
Journal: Iraqi Journal of Applied Physics Letters الرسائل العراقية في الفيزياء التطبيقية ISSN: 1999656X Year: 2008 Volume: 1 Issue: 1 Pages: 10-15
Publisher: iraqi society for alternative and renewable energy sources and techniques الجمعية العراقية لمصادر وتقنيات الطاقة البديلة والمستجدة

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Abstract

In this work, results of a mathematical analysis of the role of workpiece preheating in laser keyhole welding were presented. This analysis considered the steady-state welding as well as certain range of boundary conditions over which preheating effect would be indicated. This work is an attempt to interpret the role of preheating to increase welding depth and perform keyhole welding with high quality using physical and thermal properties of steel alloys.


Article
Optoelectronic Characteristics of As-doped Silicon Photodetectors Produced by LID Technique

Authors: A.A. Hadi --- O.A. Hamadi
Journal: Iraqi Journal of Applied Physics Letters الرسائل العراقية في الفيزياء التطبيقية ISSN: 1999656X Year: 2008 Volume: 1 Issue: 2 Pages: 23-26
Publisher: iraqi society for alternative and renewable energy sources and techniques الجمعية العراقية لمصادر وتقنيات الطاقة البديلة والمستجدة

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Abstract

In this work, optoelectronics characteristics of arsenic-doped silicon photodetectors produced by laser-induced diffusion technique were introduced. Results explained that the parameters of the photodetectors depend on laser energy and substrate temperature. Maximum Responsivity was obtained for the photodetectors prepared by laser fluence of 9.08J/cm2 at substrate temperature of 598K. The pulse response waveform of photodetectors illustrated that the rise time is not dominated by RC. Non-linearity deviation coefficient was improved by factors 2.1 for As-doped Si photodetectors when substrate temperature is raised from 300K to 598K.


Article
Effect of Self-Absorption on the Output Power of CW CO2 Laser

Authors: O.A. Hamadi --- D.N. Raouf --- N.A.K. Alrubaiey
Journal: Iraqi Journal of Applied Physics Letters الرسائل العراقية في الفيزياء التطبيقية ISSN: 1999656X Year: 2009 Volume: 2 Issue: 1 Pages: 31-34
Publisher: iraqi society for alternative and renewable energy sources and techniques الجمعية العراقية لمصادر وتقنيات الطاقة البديلة والمستجدة

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Abstract

In this work, the effect of self-absorption by molecules of the active medium on the output laser power of a low-pressure CW CO2 laser was studied. The effects of discharge current, output coupling and total gas pressure on the output laser power were discussed. It was explained that the self-absorption depends on CO2 concentration, output coupling and discharge current and there is a threshold value for both output coupling and discharge current at which the absorption is clearly effective.

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