npsm 새물리 New Physics : Sae Mulli

pISSN 0374-4914 eISSN 2289-0041
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Article

Research Paper

New Physics: Sae Mulli 2009; 58: 517-522

Published online April 30, 2009

Copyright © New Physics: Sae Mulli.

Time-resolved Photoluminescence of Self-assembled Volmer-Weber-type ZnO Nanocrystals

Se-Jeong PARK1, Yoon-Hwae HWANG1* and Hyung-Kook KIM1†, So-Hyun PARK2 and Taiha JOO2, Ik Jae LEE3, Jin Woo KIM4, Jae-Ho LEE5, Yang-Do KIM6

1Department of Nanomaterials Engineering & BK 21 Nano Fusion Technology Division, Pusan National University, Miryang 627-706
2Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 790-784
3Pohang Acceleration Laboratory, Pohang University of Science and Technology (POSTECH), Pohang 790-784
4Department of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 500-712 5Department of Materials Science and Engineering, Hong-Ik University, Seoul 121-791
6School of Materials Science and Engineering, Pusan National University, Busan 609-735

Correspondence to:yhwang@pusan.ac.kr,  hkkim@pusan.ac.kr

Abstract

Self-assembled Volmer-Weber-type ZnO nanocrystals were fabricated on Pt(111)/TiO2/SiO2/Si(100) substrates by using a RF sputtering method. The structure was analyzed by using a synchrotron X-ray method (at beamline 5C2, Pohang Acceleration Laboratory). The temperature-dependent photoluminescence of the Volmer-Weber ZnO nanocrystals was measured from 6 K to 300 K, and the time-resolved photoluminescence was measured at 12 K. We found from the X-ray experiment that the Volmer-Weber-type ZnO nanocrystals had a c-axis orientation. In the temperature-dependent photoluminescence experiment, two intensive UV emissions, 3.368 eV and 3.312 eV, were observed between 6 K and 20 K. As the temperature was increased, the two peaks combined into one at 3.299 eV. In the time-resolved photoluminescence experiment at 12 K, the dynamics of the peaks at 3.368 eV had one relaxation time of approximately 180 ps and that of the peak at 3.312 eV had three relaxation times of 79 ps, 870 ps and 2.2 ns.

Keywords: Volmer-Weber, ZnO, Nanocrystal, Time-resolved photoluminescence

라디오 주파수 마그네트론 스퍼터링 방법을 이용하여 제작한 자가 형성된 보머-웨버 (Volmer-Weber)형 산화아연 나노 결정체의 광학적 특성을 연구하였다. 먼저, 방사광 엑스선 회절 실험 (포항가속기 연구소 5C2 빔라인)을 이용하여 산화아연 나노 결정체의 구조를 분석하였고, 헬륨-카드뮴 레이저 (325 nm)를 이용하여 6 K~ 300 K 범위에서 온도 의존성 광발광 (temperature dependent photoluminescence) 특성과 펨토초 레이저를 이용한 저온 시분해 발광 (low-temperature time-resolved photoluminescence) 특성을 연구하였다. 엑스선 회절 실험에서는 보머-웨버형 산화아연 나노 결정체들이 c축 우선 방향성을 보였다. 온도 의존 광발광 실험에서는 보머-웨버형 산화아연 나노 결정체가 낮은 온도 영역 (6 K ~ 20 K)에서 3.368 eV와 3.312 eV의 두 개의 강한 자외선 발광 특성을 보이나 온도가 증가하면서 두 봉우리가 상온에서 3.299 eV의 에너지를 가지는 하나의 봉우리로 합쳐졌다. 12 K에서 수행된 시분해 광발광 실험에서 측정한 감쇄 함수는 3.368 eV 발광 봉우리의 경우 하나의 완화시간으로 분석할 수 있었으나, 3.312 eV 발광 봉우리는 세 개의 완화시간으로 분석이 가능하였다.

Keywords: 보머-웨버, 산화아연, 나노 결정체, 시분해 광발광

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