Lattice Dynamics Investigation of InAs Nanowires by Micro Raman Spectroscopy
Date Issued
2014
Date
2014
Author(s)
Hsu, Chia-Hao
Abstract
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.
Subjects
拉曼顯微光譜
砷化銦
奈米線
氣態源分子束磊晶
堆疊變異
Type
thesis
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