SOI 웨이퍼를 이용한 Top emission 방식 AMOLEDs의 스위칭 소자용 단결정 실리콘 트랜지스터

Abstract

We fabricated a single crystal silicon thin film transistor for active matrix organic light emitting displays(AMOLEDs) using silicon on insulator wafer (SOI wafer). Poly crystal silicon thin film transistor(poly-Si TFT) Is actively researched and developed nowsdays for a pixel switching devices of AMOLEDs. However, poly-Si TFT has some disadvantages such as high off-state leakage currents and low field-effect mobility due to a trap of grain boundary in active channel. While single crystal silicon TFT has many advantages such as high field effect mobility, low off-state leakage currents, low power consumption because of the low threshold voltage and simultaneous integration of driving ICs on a substrate. In our experiment, we compared the property of poly-Si TFT with that of SOI TFT. Poly-Si TFT exhibited a field effect mobility of 34 <TEX>$\textrm{cm}^2$</TEX>/Vs, an off-state leakage current of about l<TEX>${\times}$</TEX>10<TEX>$\^$</TEX>-9/ A at the gate voltage of 10 V, a subthreshold slope of 0.5 V/dec and on/off ratio of 10<TEX>$\^$</TEX>-4/, a threshold voltage of 7.8 V. Otherwise, single crystal silicon TFT on SOI wafer exhibited a field effect mobility of 750 <TEX>$\textrm{cm}^2$</TEX>/Vs, an off-state leakage current of about 1<TEX>${\times}$</TEX>10<TEX>$\^$</TEX>-10/ A at the gate voltage of 10 V, a subthreshold slope of 0.59 V/dec and on/off ratio of 10<TEX>$\^$</TEX>7/, a threshold voltage of 6.75 V. So, we observed that the properties of single crystal silicon TFT using SOI wafer are better than those of Poly Si TFT. For the pixel driver in AMOLEDs, the best suitable pixel driver is single crystal silicon TFT using SOI wafer.