Highly Enhanced Exciton Recombination Rate by Strong Electron鈥揚honon Coupling in Single ZnTe Nanobelt

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• 作者：Qing Zhang ; Xinfeng Liu ; Muhammad Iqbal Bakti Utama ; Jun Zhang ; Mar铆a de la Mata ; Jordi Arbiol ; Yunhao Lu ; Tze Chien Sum ; Qihua Xiong
• 刊名：Nano Letters
• 出版年：2012
• 出版时间：December 12, 2012
• 年：2012
• 卷：12
• 期：12
• 页码：6420-6427
• 全文大小：470K
• 年卷期：v.12,no.12(December 12, 2012)
• ISSN：1530-6992

文摘

Electron鈥損honon coupling plays a key role in a variety of elemental excitations and their interactions in semiconductor nanostructures. Here we demonstrate that the relaxation rate of free excitons in a single ZnTe nanobelt (NB) is considerably enhanced via a nonthermalized hot-exciton emission process as a result of an ultrastrong electron鈥損honon coupling. Using time-resolved photoluminescence (PL) spectroscopy and resonant Raman spectroscopy (RRS), we present a comprehensive study on the identification and the dynamics of free/bound exciton recombination and the electron鈥損honon interactions in crystalline ZnTe NBs. Up to tenth-order longitudinal optical (LO) phonons are observed in Raman spectroscopy, indicating an ultrastrong electron鈥損honon coupling strength. Temperature-dependent PL and RRS spectra suggest that electron鈥損honon coupling is mainly contributed from Light hole (LH) free excitons. With the presence of hot-exciton emission, two time constants (80 and 18 ps) are found in photoluminescence decay curves, which are much faster than those in many typical semiconductor nanostructures. Finally we prove that under high excitation power amplified spontaneous emission (ASE) originating from the electron鈥揾ole plasma occurs, thereby opening another radiative decay channel with an ultrashort lifetime of few picoseconds.

Keywords:

ZnTe nanobelts; exciton dynamics; electron鈭抪honon coupling; photoluminescence; resonant Raman spectroscopy