新型光电子材料GaAsN合金的显微光谱学研究

项目名称： 新型光电子材料GaAsN合金的显微光谱学研究

项目编号： No.10874177

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 数理科学和化学

项目作者： 谭平恒

作者单位： 中国科学院半导体研究所

项目金额： 39万元

中文摘要： 掺氮的III-V 族半导体材料GaNAs因其具有异常的光学性质而成为倍受瞩目的新型光电子材料。理解其独特的物理性质将会有力地促进Ga(In)NAs材料在光电子器件方面的应用。本项目主要利用显微光致发光和显微共焦拉曼技术在常温和液氮温度下研究了N 组分从0.0%到1.7%的GaAsN 合金。发现GaAsN材料E0+ESO能级具有共振激发效应，而E+能级却没有。在低温下，在GaAsN合金中观察到七阶的共振拉曼信号，但在GaAs体材料却不能，揭示了极少N的掺入就能显著改变GaAs材料的离子特性。随着N组分的增大，E+能级荧光峰的激发光强度依赖系数越小，且载流子的热激合能越大。同激光波长激发了各组分的GaAsN合金的共振拉曼光谱,发现低N组分合金2LO/LO的共振拉曼线型发生显著的展宽，说明在低N组分时E0+ESO和E+能级发生了能级混合作用。通过将布拉格体光栅技术集成到单光栅光谱仪中，发展了小于40波数的高透过率低波数拉曼信号的测试技术。将此技术应用到GaASN材料，观察到自于L和X点声学声子的共振拉曼峰，这些拉曼峰都与E+能级共振。所有结果都证实了我们所提出的E+能级来源的新模型。

中文关键词： GaAsN材料;拉曼光谱;光致发光光谱;离子性;载流子热化

英文摘要： N-induced perturbation to the electronic band structure is unusually strong in dilute GaAsN alloys. The understanding of the peculiar physical properties of GaAsN alloys is the fundamental issue for their promising applications in the optoelectronic fields. In this project, we study the optical properties of GaAsN alloys with N content from 0.0% to 1.7% at room and liquid nitrogen temperature using micro-photoluminescence and micro-Raman spectroscopy. In comparison to the E+ level, the E0+Eso level can be significantly excited resonantly. At liquid nitrogen temperature, seventh order resonant Raman peaks was observed in GaAsN alloys, while in bulk GaAs, only third-order Raman mode can be observed. This indicates that a small amount of N has surprisingly led to the typical characters of bulk states of strongly ionic semiconductors in GaAsN alloy. With the increase of N content, E+ peak intensity dependent on the excitation power become weaker while the hot electrons within the E+ band are found to exhibit higher unusual thermalization. The resonant Raman profile of 2LO/LO is significantly broadened for lower N content, such as 0.1%, which indicates that there exists the level mixing between E+ and E0+Eso levels. By integration of Bragg volume grating into a single monochromator, we developed the technique for measurement of ultralow frequency modes below 40 cm-1 with very high throughput. With this technique, Raman peaks from L and X points were observed in GaAsN alloys, which are resonant with E+ level. All the results confirms that the E+ level in GaAsN alloy is comprised of the contributions of a fairly large set of conduction band states near the L point, which are perturbed by N doping to different degrees.

英文关键词： GaAsN; Raman Spectroscopy; Photoluminescence;ionic semiconductor;carrier thermalization