title: Effect of growth temperature on the morphology and phonon properties of InAs nanowires on Si substrates.
abstract: Catalyst-free, vertical array of InAs nanowires (NWs) are grown on Si (111) substrate using MOCVD technique. The as-grown InAs NWs show a zinc-blende crystal structure along a < 111 > direction. It is found that both the density and length of InAs NWs decrease with increasing growth temperatures, while the diameter increases with increasing growth temperature, suggesting that the catalyst-free growth of InAs NWs is governed by the nucleation kinetics. The longitudinal optical and transverse optical (TO) mode of InAs NWs present a phonon frequency slightly lower than those of InAs bulk materials, which are speculated to be caused by the defects in the NWs. A surface optical mode is also observed for the InAs NWs, which shifts to lower wave-numbers when the diameter of NWs is decreased, in agreement with the theory prediction. The carrier concentration is extracted to be 2.25 × 1017 cm-3 from the Raman line shape analysis. A splitting of TO modes is also observed.PACS: 62.23.Hj; 81.07.Gf; 63.22.Gh; 61.46.Km.
authors.affiliation: Key Laboratory of Semiconductor Material Science, Institute of Semiconductors, Chinese Academy of Science, Beijing 100083, People's Republic of China. yhchen@semi.ac.cn.
authors.forename: Tianfeng
authors.initials: T
authors.lastname: Li
authors.forename: Yonghai
authors.initials: Y
authors.lastname: Chen
authors.forename: Wen
authors.initials: W
authors.lastname: Lei
authors.forename: Xiaolong
authors.initials: X
authors.lastname: Zhou
authors.forename: Shuai
authors.initials: S
authors.lastname: Luo
authors.forename: Yongzheng
authors.initials: Y
authors.lastname: Hu
authors.forename: Lijun
authors.initials: L
authors.lastname: Wang
authors.forename: Tao
authors.initials: T
authors.lastname: Yang
authors.forename: Zhanguo
authors.initials: Z
authors.lastname: Wang