Highly enhanced second-order nonlinear susceptibilities in tailored GaN–AlGaN–AlN quantum well structures

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• 作者：A. Rostami ; H. Baghban Asghari Nejad ; H. Rasooli Saghai
• 关键词：Second-order susceptibility ; Strained quantum well ; Genetic algorithm ; Electroabsorption
• 刊名：Physica B
• 出版年：2008
• 期刊代码：53_09214526
• 类别：ph
• 出版时间：1 August 2008
• 卷：403
• 期：17
• 页码：2725-2731
• 文件大小：768 K

摘要

A tailoring proposal for design of the strained quantum well structures, optimized with respect to the intersubband resonant second-order nonlinear properties, is presented in this article. A genetic-algorithm-based method is used in order to obtain the optimal potential shape, doping concentration and location in strained GaN–AlGaN–AlN quantum wells, and the structures are analyzed by a numerical solution of the Schrödinger–Poisson self-consistent method. In general form two types of asymmetric structures with remarkable results are obtained with different resonant frequencies, and in both cases results show a considerably high enhancement in the magnitude of the second-order nonlinear susceptibilities in higher resonant frequencies in comparison with a single quantum well structure with the same well width (5.02×10⁻⁸ m/V at name="mml1">n class="inlMMLBox">nce?_ob=MathURL&_method=retrieve&_udi=B6TVH-4RV7YFV-1&_mathId=mml1&_user=1067359&_cdi=5535&_rdoc=37&_acct=C000050221&_version=1&_userid=10&md5=8c5094b8bd24d261e63abbb963efb2f4">ncedirect.com/cache/MiamiImageURL/B6TVH-4RV7YFV-1-P/0?wchp=dGLzVzz-zSkzS" alt="View the MathML source" title="View the MathML source" align="absbottom" border="0" height=13 width="92"/>n>to 2.9×10⁻⁵ m/V at name="mml2">n class="inlMMLBox">nce?_ob=MathURL&_method=retrieve&_udi=B6TVH-4RV7YFV-1&_mathId=mml2&_user=1067359&_cdi=5535&_rdoc=37&_acct=C000050221&_version=1&_userid=10&md5=b0d0a92ede70ea917228eb87bfbf159c">ncedirect.com/cache/MiamiImageURL/B6TVH-4RV7YFV-1-Y/0?wchp=dGLzVzz-zSkzS" alt="View the MathML source" title="View the MathML source" align="absbottom" border="0" height=13 width="92"/>n>and 2.43×10⁻⁵ m/V at name="mml3">n class="inlMMLBox">nce?_ob=MathURL&_method=retrieve&_udi=B6TVH-4RV7YFV-1&_mathId=mml3&_user=1067359&_cdi=5535&_rdoc=37&_acct=C000050221&_version=1&_userid=10&md5=7d4dc45852dc6be92a67d788d9db5e9f">ncedirect.com/cache/MiamiImageURL/B6TVH-4RV7YFV-1-10/0?wchp=dGLzVzz-zSkzS" alt="View the MathML source" title="View the MathML source" align="absbottom" border="0" height=13 width="100"/>n>). The optimized structures exhibit considerable absorption coefficient and electroabsorption properties due to high dipole transition matrix element, high dopant concentration and reasonable Fermi level.