Electrical properties of Al-doped and Ga-doped ZnO thin film by pulsed laser deposition

Abstract

Al-doped ZnO(AZO) and Ga-doped ZnO(GZO) thin films were grown on (001)-oriented SrTiO by the pulsed laser deposition technique with varing Al and Ga concentration. The room-temperature resistivity of AZO films was found to decrease with Al concentration up to 0.5%, and then increase. On the other side, the room-temperature resistivity of GZO films was found to decrease with Ga concentration up to 1%, and then increase. The minimum resistivity of AZO and GZO was 0.033 and 0.024 Ohm cm, respectively. The temperature dependence of resistivity measurements were carried out on AZO and GZO films in the temperature range of 4 to 300 K. The resistivity of AZO and GZO have different temperature dependence when doping rate increases and decreases, respectively. The films and heterostructures were characterized by high-resolution x-ray diffraction (XRD) including theta-2theta analysis, omega-scan rocking curves and phi-scan . The surface morphology of the films was analysed by atomic force microscopy(AFM)

Pulsed laser deposition(PLD)을 이용하여 STO 기판 위에 증착한 Al-doped ZnO(AZO)와 Ga-doped ZnO(GZO) 박막을 도핑에 따라 증착을 하였다. AZO 박막의 상온 저항 값은 0.5%도핑까지 감소하였고, 다시 도핑이 증가함에 따라 저항 값이 증가하였다. 이에 반하여 GZO 박막의 상온 저항 값은 1%까지 감소하였고, 그 후 다시 증가하였다. AZO 박막과 GZO 박막의 최소 저항 값은 각각0.033Ωcm와 0.024Ωcm로 나타났다. 각각 박막의 저항의 온도 의존도는 4K에 서부터 300K까지 온도를 변화시켜가며 측정하였다. 이 박막의 온도에 따른 전기특성은 박막의 도핑 비율에 따라 각각 다른 온도 의존성을 나타냈다. 성장된 샘플 구조적 특성은 high-resolution x-ray diffraction(HRXRD)을 이용하여 omega-scan rocking curve 그리고 phi-scan을 수행하였다. 그리고 표면의 형태는 atomic force microscopy(AFM)을 통하여 측정하였다.