| Summary: | 碩士 === 國立臺灣海洋大學 === 光電科學研究所 === 93 === For the first time, one dimensional InN nano-tips were fabricated with gold as the catalyst using metal organic chemical vapor deposition. The morphology dependence of nano-tips on substrate temperature, pressure, and gas flow rate was investigated; further, the infrared photoluminescence (IR-PL) spectra of InN nanotips as well as nanobelts, nanowires, and nanowires encapsulated by GaN were measured.
Observed through scanning electron microscopy (SEM), the single crystalline InN nanotip was revealed to be a tapered hexagon with 100~200nm in diameter and 1~3um in length. The IRPL showed a peak centered at 0.776eV, in which intensity is nearly temperature independent and could be attribute to the near band edge emission in InN. In contrast, the IR-PL spectrum of InN nanowires is susceptible to damage under high power laser; However, as the nanowire was encapsulated with GaN, the damaging threshold of nanowires can be greatly improved. Moreover, apparent amplified spontaneous emission and lasing phenomenon were observed both on InN nanotips and nanobelts, which behavior has however not observed in nanowires. A possible reason is due to the extremely thin diameter, which has lower laser scattering cross section. After carefully examination, the observed lasing phenomenon is very likely due to the random lasing mechanism, which was firstly observed in InN.
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