Papers by Author: Hee Hwan Choe

Abstract: In order to improve long term stability of a-Si:H TFT for AM-OLED application a new driving method compensating Vth shift requires a new device structure of which hole injection is enhanced. ITO film was investigated for the hole injection material because it is essential material for display devices and has high work function favorable for hole injection. From I-V characteristics of TFTs with two types of source and drain material, i.e. Cr and ITO, the contact properties were measured and compared. Although electron injection property of ITO was worse than Cr, hole injection property was comparable to that of Cr.

Abstract: Amorphous silicon thin films were deposited below 160oC on PES plastic films using PECVD. After thin film deposition using PECVD, thin film failures such as film delamination and cracking often occurred. For successful growth of thin films (about 2000 Å) without their failures, it is necessary to solve the critical problem related to the internal compressive stress (some GPa) leading to delamination at a threshold thickness value of the films. The Griffith’s theory explains the failure process by looking at the excess of elastic energy inside the film, which overcomes the cohesive energy between film and substrate. In this work, reducing a-Si layer film thickness and optimizing a barrier SiNx layer have produced stable a-Si films at 150oC, over PES substrates.