ε-Ga2O3 박막 성장 및 MSM UV photodetector의 전기광학적 특성
Thin film growth of ε-Ga2O3 and photo-electric properties of MSM UV photodetectors
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본 연구에서는 Ga2O3 박막의 구조적 특성과 Ti/Au 전극을 증착하여 제작된 metal-semiconductor-metal (MSM) photodetector 소자의 광학적, 전기적 특성에 대해 연구하였다. 유기 금속 화학 증착법(metal organic chemical vapor deposition, MOCVD)을 이용해 서로 다른 온도에서 Ga2O3 박막을 성장하였다. 성장온도에 따라 Ga2O3의 결정상이 ε-상에서β-상으로 변화하는 것을 확인할 수 있었다. X-선 회절 분석(X-ray diffraction, XRD) 결과로 ε-Ga2O3 의 결정구조를 확인하였 고, 주사 전자 현미경(scanning electron microscopy, SEM) 이미지로 결정구조의 형성 메커니즘에 대해 논의하였다. 음극선 발광(Cathode luminescence, CL) 측정으로 Ga2O3의 발광성 천이에 관여하는 에너지 준위의 형성 원인에 대해 논의하였다. 제작된 MSM photodetector 소자의 외부 광에 대한 전류-전압 특성과 시간 의존성 on/off 광 응답 특성을 통해 ε-Ga2O3로 제작한 photodetector는 가시광보다 266 nm UV 파장 영역에서 훨씬 뛰어난 광전류 특성을 보이는 것을 확인하였다.
Abstract
In this study, we investigated the structural properties of Ga2O3 thin films and the photo-electrical properties of metal-semiconductor-metal (MSM) photodetectors deposited by Ti/Au electrodes. Ga2O3 thin films were grown at different temperatures using metal organic chemical vapor deposition (MOCVD). The crystal phase of Ga2O3 changed from ε-phase to β-phase depending on the growth temperature. The crystal structure of ε-Ga2O3 was confirmed by X-ray diffraction (XRD) analysis and the formation mechanism of crystal structure was discussed by scanning electron microscopy (SEM) images. From the results of current-voltage (I-V) and time-dependent photoresponse characteristics under the illumination of external lights, we confirmed that the MSM photodetector fabricated by ε-Ga2O3 showed much better photocurrent characteristics in the 266 nm UV range than in the visible range
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