밀착형 문자감지소자의 제작 Ⅱ

국문 초록 (Abstract)

본 연구에서는 a-Si:H 광다이오드와 a-Si:H TFT를 동일 유리기판위에 집적시킨 밀착형 문자감지소자를 제작하였다. a-Si:H 광다이오드의 정공차단막인 a-SiN:H막의 두께를 300Å, 광도전막인 a-Si:H막의 두께를 6000Å 그리고 전자차단막인 p-a-Si:H막의 두께를 1000 Å으로 하여 ITO/a-SiN:H/a-Si:H/p-a-Si:H/Al 광다이오드를 제작하였다. 또한 밀착형 문자감지소자의 구동을 위해 a-SiN:H를 게이트 절연막으로 역 스태거드형 a-Si:H를 제작하고 그 특성을 조사하였다.

다국어 초록 (Multilingual Abstract)

In this study, we fabricated the integrated contact-type image sensor with a-Si:H potodiode and a-Si:H TFT on glass substrate. First, for this study, we deposited and investigated a-SiN:H films for hole blocking layer of a-Si:H photodiode and gate insulating layer of a-Si:H TFT by RF glow discharge decomposition (PECVD) using SiH_4 and NH_3 gas mixtures. When the NH_3/SiH_4 gas ratio, substrate temperature, RF power, gas pressure, thickness were 10, 250℃, 20 W, 500 mTorr, and 2000 Å, respectively, the dielectric constant of a-SiN:H film was 4 and optical bandgap was 3 eV. It can be concluded that the a-SiN:H film is applicable to the hole blocking layer of a-Si:H photodiode and gate insulating layer of a-Si:H TFT.
We fabricated ITO/a-SiN:H/a-Si:H/p-a-Si:H/Al photodiode, when the hole blocking layer, photoconductive layer and electron blocking layer of a-Si:H photodiode were 300Å, 6000 Å and 1000 Å, respectively. From the current-voltage characteristics of this photodiode, the dark current was suppressed at less then 1.5 pA under applied voltage of 10 V. Photosensitivity was 0.97 under applied voltage of 3 V. Also spectral respose characteristic was improved at short wavelenth region and the peak respose was at 540㎚.
Also we fabricated and investigated a-Si:H TFT with a-SiN:H insulating layer for contact-type image sensor. In this case, gate electode of a-Si:H TFT was Al with 2000 Å. When a-SiN:H gate insulating layer, a-Si:H semiconductor layer and n^+-a-Si:H layer of a-Si:H TFT were 2000 Å, 2000 Å and 500 Å, respectively. When a-Si:H TFT with channel length of 50 ㎛ and channel width of 1000 ㎛ was annealed at 200 ℃ for 2 hours, ON/OFF current ratio was 105, thershold voltage was 6.3 V and field effect mobility was 0.15 cm2/V·sec. From these results, a-Si:H TFT will be applicable to switching device of contact-type image sensor.