Exciton scattering mechanism in a single semiconducting MgZnO nanorod

Jinkyoung Yoo, Dang Le Si, Bonghwan Chon, Taiha Joo and Gyu-Chul Yi \"Exciton scattering mechanism in a single semiconducting MgZnO nanorod\", Nano Letters, 12 (2), 556-561 (2012.02.08)
참여연구원 : 이규철 교수님, 유진경 박사

엑시톤(exciton)은 반도체 속의 전도전자와 가전대의 정공의 쌍을 의미하는 것으로 반도체 광소자에 널리 응용되는 현상이다. 기존에 bulk에서 관찰되던 현상과 새롭게 떠오르는 나노사이즈의 반도체 물질에서 관찰되는 현상은 그 물리적 특성이 다르다. 위 논문에서는 마그네슘이 도핑된 산화아연(MgZnO) 나노막대에서의 엑시톤 현상을 관찰하고 TRPL 측정을 통해 5 ~ 80K의 저온에서 엑시톤의 lifetime 증가에 따르는 diffusion length의 증가를 확인하였다.

Excitonic phenomena, such as excitonic absorption and emission, have been used in many photonic and optoelectronic semiconductor device applications. As the sizes of these nanoscale materials have approached to exciton diffusion lengths in semiconductors, a fundamental understanding of exciton transport in semiconductors has become imperative. We present exciton transport in a single MgZnO nanorod in the spatiotemporal regime with several nanometer-scale spatial resolution and several tens of picosecond temporal resolution. This study was performed using temperature-dependent cathodoluminescence and time-resolved photoluminescence spectroscopies. The exciton diffusion length in the MgZnO nanorod decreased from 100 to 70 nm with increasing temperature in the range of 5 and 80 K. The results obtained for the temperature dependence of exciton diffusion length and luminescence lifetime revealed that the dominant exciton scattering mechanism in MgZnO nanorod is exciton–phonon assisted piezoelectric field scattering.

Keywords: Exciton scattering; exciton diffusion; MgZnO; nanorod; quantum structure; cathodoluminescence; time-resolved photoluminescence