德国Paul-Drude研究所Uwe Jahn博士将于11月25日来我所学术交流，并在“黄昆半导体科学技术论坛”上作第86期报告，欢迎广大科研人员及研究生积极参加!

报告题目: Scanning electron microscope cathodoluminescence of GaN/(Al,Ga)N nanocolumns

报告人: Dr. U. Jahn (Paul-Drude-Institute Berlin, Germany)

时间: 2008年11月25日(星期二) 上午 9:00

地点: 中国科学院半导体研究所学术会议中心

Abstract:A widely investigated route of the fabrication of nearly strain and defect-free GaN is the growth of GaN nanocolumns by catalyst-free MBE or MOCVD on various substrates including Si. Heterostructures such as quantum wells (QW) have to be integrated into these columns for the application in LEDs. The luminescence distribution of GaN(Al,Ga)N nanocolumns is investigated by spatially and spectrally resolved cathodoluminescence (CL). The optical transition energy of the Qdisks formed in the GaN/(Al,Ga)N nanocolumn structures depends strongly on the diameter of the Qdisks and on the excitation density, indicating the influence of the lateral strain distribution and an effective screening of the internal electrical field within the Qdisks. For thin Qdisks, the strain distribution leads to a separate confinement of electrons and holes at the center and periphery of the thin Qdisks. A sophisticated strain engineering is needed for a high quantum efficiency and narrow optical emission of Qdisk structures.

报告人简介：Dr. Uwe Jahn is a senior scientist at the Paul-Drude-Institute for Solid State Electronics in Berlin, Germany. He got his PhD in 1982 at the Friedrich-Schiller-University Jena, German Democratic Republic. Now his main research field is spatially resolved cathodoluminescence (CL) and photoluminescence of bulk semiconductors and nanostructures. The emphasis of his current activities is investigation and characterization of GaN-related semiconductor layers and nanostructures grown by MBE and MOCVD.

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