npsm 새물리 New Physics : Sae Mulli

pISSN 0374-4914 eISSN 2289-0041
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Article

Research Paper

New Physics: Sae Mulli 2012; 62: 78-83

Published online January 31, 2012 https://doi.org/10.3938/NPSM.62.78

Copyright © New Physics: Sae Mulli.

Photocurrent Characteristics of Ferroelectric Pb(Zr0.3Ti0.7)O3 Thin Films

Sungchul KIM1, Byungmoon JIN1, Sung Sik WON2, Chang Won AHN2, Jungmin PARK2, Hae Jin SEOK2, Song A CHAE2, Ill Won KIM*2, Young Soo KIM3

1Department of Physics, Dong-eui University, Busan 614-714

2Department of Physics, University of Ulsan, Ulsan 680-749
3Bangeojin High school, Ulsan 681-749

Correspondence to:kimiw@mail.ulsan.ac.kr

Abstract

In materials without a center of symmetry, such as ferroelectric materials, a photocurrent can be produced in a homogeneous medium under uniform illumination, the so called ferroelectric photovoltaic effect (FPE). The FPE is an effect that has an extremely large photovoltage (> kV) and a photocurrent proportional to the magnitude of the polarization and the charge carrier separation. We fabricated Pb(Zr0.3Ti0.7)O3 (PZT) ferroelectric thin films on Pt/Ti/SiO2/Si substrates by using a sol-gel technique and investigated the photocurrent properties. In the measurement of the photocurrent, the maximum photocurrent density of the PZT films was obtained at a wavelength of 350 nm. The band gap energy of the PZT film was 3.5 eV, which is consistent with that of the bulk PZT material. From the I-V measurement, the Schottky barriers between the Pt (top electrode)/PZT film and the PZT film/Pt (bottom electrode) were symmetric.

Keywords: Ferroelectric, Photovoltaic, Photocurrent, Thin film, PZT, Ferroelectric photovoltaic

결정구조 상 대칭중심을 가지지 않는 강유전 물질에 빛이 입사되면 광전류가 발생되는데 이 현상을 강유전체 광기전 효과 (ferroelectric photovoltaic effect, FPE)라 한다. FPE는 매우 큰 광전압(>kV)을 발생 할 수 있는 장치로 이때 생성되는 광전류는 강유전체의 분극과 전하운반체의 분리에 기인한다. 졸-겔 방법으로 Pt/Ti/SiO2/Si 기판 위에 Pb(Zr0.3Ti0.7)O3 (PZT) 강유전체 박막을 제조하여 광전류 특성을 조사하였다. 입사광의 파장에 따른 PZT 박막의 광전류 측정결과 파장 350 nm에서 최대 광전류밀도 -93.3 nA/cm2을 나타내었으며 밴드갭 에너지는 3.5 eV 이었다. I-V 측정으로부터 상부전극/PZT박막과 하부전극/PZT박막 사이의 두 경계면에 형성되는 쇼트키 장벽은 대칭을 이루었다.

Keywords: 강유전체, 광기전력 효과, 광전류, 박막, PZT, Ferroelectric Photovoltaic

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