Lattice Dynamics Investigation of InAs Nanowires by Micro Raman Spectroscopy

• Main Authors: Chia-Hao Hsu, 許家豪
• Other Authors: Hao-Hsiung Lin
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/46896553096374876040

碩士 === 國立臺灣大學 === 電子工程學研究所 === 102 === In this thesis, the optical and structural properties of InAs nanowires grown by GSMBE have been investigated by μ-Raman spectroscopy. To begin with, the single nanowire signal detection is achieved, and we observed the LO, TO and SO modes of InAs, which are analyzable. Secondly, we discovered that the optical modes of NWs are red-shifted compared with bulk counterparts, and the selection rules are different too. The possibility of laser heating is eliminated via power-variant measurement, in which we haven’t observed mode shifting. By performing measurements in different configurations, we attribute the 3~4 cm-1 redshift of TO mode under X(YY)X to the appearance of E2 mode of Wurzite structure caused by stacking variance in NW. The Wurzite-B1 mode, induced by lattice disorder, is also observed under X(ZZ)X &; X(YZ)X. In addition, the blue-shifting of Raman modes after RTA is observed for the first time, and the phenomena is corresponded to the relaxation of interfacial strain between ZB&;WZ structures. The redshift caused by interfacial strain is about 2 cm-1 for both TO &; LO modes.