DC and AC Gate-Bias Stability of Nanocrystalline Silicon Thin-Film Transistors Made on Colorless Polyimide Foil Substrat
- PDF / 203,297 Bytes
- 6 Pages / 432 x 648 pts Page_size
- 69 Downloads / 145 Views
DC and AC Gate-Bias Stability of Nanocrystalline Silicon Thin-Film Transistors Made on Colorless Polyimide Foil Substrates I-Chung Chiu1, I-Chun Cheng1,2,*, Jian Z. Chen3, Jung-Jie Huang4, Yung-Pei Chen5 Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei, 10617 Taiwan 2 Department of Electrical Engineering, National Taiwan University, Taipei, 10617 Taiwan 3 Institute of Applied Mechanics, National Taiwan University, Taipei, 10617 Taiwan 4 Department of Materials Science and Engineering, MingDao University, Changhua, 52345 Taiwan 5 Display Technology Center, Industrial Technology Research Institute, Hsinchu, 31040 Taiwan 1
ABSTRACT Staggered bottom-gate hydrogenated nanocrystalline silicon (nc-Si:H) thin-film transistors (TFTs) were demonstrated on flexible colorless polyimide substrates. The dc and ac bias-stress stability of these TFTs were investigated with and without mechanical tensile stress applied in parallel to the current flow direction. The findings indicate that the threshold voltage shift caused by an ac gate-bias stress was smaller compared to that caused by a dc gate-bias stress. Frequency dependence of threshold voltage shift was pronounced in the negative gate-bias stress experiments. Compared to TFTs under pure electrical gate-bias stressing, the stability of the nc-Si:H TFTs degrades further when the mechanical tensile strain is applied together with an electrical gate-bias stress. INTRODUCTION In recent years, flexible electronics have attracted considerable interest. They are the foundational technology for building electronics on foldable, rollable, and even stretchable surfaces. Their main application comprises electronic books, cell phones, roll-up displays, portable displays, and so on. Hydrogenated amorphous silicon (a-Si:H) thin-film transistors (TFTs) are the industrial technology standard for active matrix (AM) liquid crystal displays (LCDs). This leads to extensive studies on flexible a-Si:H TFTs [1-3]. Hydrogenated nanocrystalline silicon (nc-Si:H) has been considered an alternative active material for TFTs due to its higher electron mobility compared to a-Si:H [4-6], with CMOS-capability [7], and demonstrating better stability against light-induced degradation [8] and electrical bias stress [9]. Most significant is its fabrication process being fully compatible with current display massproduction facilities. During the fabrication or operation of flexible electronics, the TFTs may suffer from mechanical stress. The on-plastic TFTs must sustain functionality either during or after mechanical deformation. This study demonstrated nc-Si:H TFTs on colorless polyimide foil substrates and investigated their electrical stability against a dc and an ac bias stress with and without mechanical bending.
259
EXPERIMENT A glass plate was used as the supporting substrate. A layer of debonding material and a 20 ȝm experimental colorless polyimide were consecutively coated onto the supporting substrate. Prior to TFT fabrication, a 300 nm SiNx buffer layer was de
Data Loading...
