Silicon germanium photo-blocking layers for a-IGZO based industrial display

Su Hyoung Kang; Sangmin Kang; Seong Chae Park; Jong Bo Park; Youngjin Jung; Byung Hee Hong

doi:10.1038/s41598-018-35222-9

Silicon germanium photo-blocking layers for a-IGZO based industrial display

Sci Rep. 2018 Dec 3;8(1):17533. doi: 10.1038/s41598-018-35222-9.

Authors

Su Hyoung Kang¹, Sangmin Kang^{1

2}, Seong Chae Park³, Jong Bo Park¹, Youngjin Jung¹, Byung Hee Hong^{4

5}

Affiliations

¹ Department of Chemistry, College of Natural Science, Seoul National University, Seoul, 08826, Korea.
² Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA.
³ Graphene Research Center, Advanced Institute of Convergence Technology, Seoul National University, Suwon, 16229, Korea.
⁴ Department of Chemistry, College of Natural Science, Seoul National University, Seoul, 08826, Korea. byunghee@snu.ac.kr.
⁵ Graphene Research Center, Advanced Institute of Convergence Technology, Seoul National University, Suwon, 16229, Korea. byunghee@snu.ac.kr.

Abstract

Amorphous indium- gallium-zinc oxide (a-IGZO) has been intensively studied for the application to active matrix flat-panel display because of its superior electrical and optical properties. However, the characteristics of a-IGZO were found to be very sensitive to external circumstance such as light illumination, which dramatically degrades the device performance and stability practically required for display applications. Here, we suggest the use for silicon-germanium (Si-Ge) films grown plasma-enhanced chemical vapour deposition (PECVD) as photo-blocking layers in the a-IGZO thin film transistors (TFTs). The charge mobility and threshold voltage (V_th) of the TFTs depend on the thickness of the Si-Ge films and dielectric buffer layers (SiN_X), which were carefully optimized to be ~200 nm and ~300 nm, respectively. As a result, even after 1,000 s illumination time, the V_th and electron mobility of the TFTs remain unchanged, which was enabled by the photo-blocking effect of the Si-Ge layers for a-IGZO films. Considering the simple fabrication process by PECVD with outstanding scalability, we expect that this method can be widely applied to TFT devices that are sensitive to light illumination.