Photobias Instability of High Performance Solution Processed Amorphous Zinc Tin Oxide Transistors

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• 作者：Yoon Jang Kim ; Bong Seob Yang ; Seungha Oh ; Sang Jin Han ; Hong Woo Lee ; Jaeyeong Heo ; Jae Kyeong Jeong ; Hyeong Joon Kim
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2013
• 出版时间：April 24, 2013
• 年：2013
• 卷：5
• 期：8
• 页码：3255-3261
• 全文大小：465K
• 年卷期：v.5,no.8(April 24, 2013)
• ISSN：1944-8252

文摘

The effects of the annealing temperature on the structural and chemical properties of soluble-processed zinc鈥搕in鈥搊xide (ZTO) films were examined by transmission electron microscopy, atomic force microscopy, high resolution X-ray reflectivity, and X-ray photoelectron spectroscopy. The density and purity of the resulting ZTO channel layer increased with increasing annealing temperature, whereas the oxygen vacancy defect density decreased. As a result, the device performance of soluble ZTO thin film transistors (TFTs) was improved at higher annealing temperature. Although the 300 掳C-annealed ZTO TFT showed a marginal field-effect mobility (渭_FE) and high threshold voltage (V_th) of 0.1 cm²/(V s) and 7.3 V, respectively, the 500 掳C-annealed device exhibited a reasonably high 渭_FE, low subthreshold gate swing (SS), V_th, and I_on/off of 6.0 cm²/(V s), 0.28 V/decade, 0.58 V, and 4.0 脳 10⁷, respectively. The effects of dark negative bias stress (NBS) and negative bias illumination stress (NBIS) on the degradation of transfer characteristics of ZTO TFTs were also investigated. The instability of V_th values of the ZTO TFTs under NBS and NBIS conditions was suppressed with increasing annealing temperature. To better understand the charge trapping mechanism, the dynamics of V_th shift with NBS and NBIS time for all ZTO TFTs was analyzed on the basis of the stretched exponential relaxation. The negative V_th shift for each transistor was accelerated under NBIS conditions compared to NBS, which resulted in a higher dispersion parameter and smaller relaxation time for NBIS degradation. The relaxation time for NBS and NBIS instability increased with increasing annealing temperature, which is discussed on the basis of the transition mechanism of oxygen vacancy defects.

Keywords:

zinc tin oxide (ZTO); soluble process; annealing temperature; thin film transistors (TFTs); bias stress instability; light stress instability