https://scholar.korea.ac.kr/handle/2021.sw.korea/2418 2026-04-09T14:33:33Z 2026-04-09T14:33:33Z Goh, Youngin Ahn, Jaehan Lee, Jeong Rak Park, Wan Woo Park, Sang-Hee Ko Jeon, Sanghun https://scholar.korea.ac.kr/handle/2021.sw.korea/81862 2024-11-15T14:01:45Z 2017-10-25T00:00:00Z

Title: Efficient Suppression of Defects and Charge Trapping in High Density In-Sn-Zn-O Thin Film Transistor Prepared using Microwave-Assisted Sputter Authors: Goh, Youngin; Ahn, Jaehan; Lee, Jeong Rak; Park, Wan Woo; Park, Sang-Hee Ko; Jeon, Sanghun Abstract: Amorphous oxide semiconductor-based thin film transistors (TFTs) have been considered as excellent switching elements for driving active-matrix organic light-emitting diodes (AMOLED) owing to their high mobility and process compatibility. However, oxide semiconductors have inherent defects, causing fast transient charge trapping and device instability. For the next-generation displays such as flexible, wearable, or transparent displays, an active semiconductor layer with ultrahigh mobility and high reliability at low deposition temperature is required. Therefore, we introduced high density plasma microwave assisted (MWA) sputtering method as a promising deposition tool for the formation of high density and high-performance oxide semiconductor films. In this paper, we present the effect of the MWA sputtering method on the defects and fast charge trapping in In-Sn-Zn-O (ITZO) TFTs using various AC device characterization methodologies including fast I-V, pulsed I-V, transient current, low frequency noise, and discharge current analysis. Using these methods, we were able to analyze the charge trapping mechanism and intrinsic electrical characteristics, and extract the subgap density of the states of oxide TFTs quantitatively. In comparison to conventional sputtered ITZO, high density plasma MWA-sputtered ITZO exhibits outstanding electrical performance, negligible charge trapping characteristics and low subgap density of states. High-density plasma MWA sputtering method has high deposition rate even at low working pressure and control the ion bombardment energy, resulting in forming low defect generation in ITZO and presenting high performance ITZO TFT. We expect the proposed high density plasma sputtering method to be applicable to a wide range of oxide semiconductor device applications.

2017-10-25T00:00:00Z Kim, Taeho Park, Sungho Jeon, Sanghun https://scholar.korea.ac.kr/handle/2021.sw.korea/82211 2024-11-14T21:05:02Z 2017-09-19T00:00:00Z

Title: Fast and slow transient charging of Oxide Semiconductor Transistors Authors: Kim, Taeho; Park, Sungho; Jeon, Sanghun Abstract: The comprehension of the governing mechanism which affects device instability is one of the most important requirements for the formation of reliable oxide-thin film transistors (TFTs). However, a quantitative analysis of the dominant mechanism of device instability, which stems from charge trapping induced by defects at the oxide semiconductor interface as well as in its bulk, has not yet been systematically performed. In this study, we examined subgap states, charge-transport dynamics, and various trap characteristics of oxide TFTs by multi-frequency C-V, pulse I-V, and transient current methods to achieve a comprehensive understanding of carrier transport and charge trapping mechanisms. We found that the charge trapping behavior of the tested amorphous InHfZnO (alpha-IHZO) TFT follows a multi-trapping mechanism, such as temperature-independent fast transient charge trapping by resonant drift of the injected electron and temperature-dependent slow transient charge trapping by charge transport from occupied to unoccupied traps. Understanding fast charging and slow charging described in this study can help to understand the root cause of device instability of oxide TFTs and ultimately improve stability and reliability characteristics.

2017-09-19T00:00:00Z Ko, Eunah Lee, Hyunjae Goh, Youngin Jeon, Sanghun Shin, Changhwan https://scholar.korea.ac.kr/handle/2021.sw.korea/82485 2024-11-15T03:49:37Z 2017-09-01T00:00:00Z

Title: Sub-60-mV / decade Negative Capacitance FinFET With Sub-10-nm Hafnium-Based Ferroelectric Capacitor Authors: Ko, Eunah; Lee, Hyunjae; Goh, Youngin; Jeon, Sanghun; Shin, Changhwan Abstract: The negative capacitance (NC) of ferroelectric materials has paved the way for achieving sub-60-mV/decade switching feature in complementary metal-oxide-semiconductor (CMOS) field-effect transistors, by simply inserting a ferroelectric thin layer in the gate stack. However, in order to utilize the ferroelectric capacitor (as a breakthrough technique to overcome the Boltzmann limit of the device using thermionic emission process), the thickness of the ferroelectric layer should be scaled down to sub-10-nm for ease of integration with conventional CMOS logic devices. In this paper, we demonstrate an NC fin-shaped field-effect transistor (FinFET) with a 6-nm-thick HfZrO ferroelectric capacitor. The performance parameters of NC FinFET such as on-/off-state currents and subthreshold slope are compared with those of the conventional FinFET. Furthermore, a repetitive and reliable steep switching feature of the NC FinFET at various drain voltages is demonstrated.

2017-09-01T00:00:00Z Park, Junghak Woo, Hyunsuk Jeon, Sanghun https://scholar.korea.ac.kr/handle/2021.sw.korea/82397 2024-11-18T02:25:22Z 2017-09-01T00:00:00Z

Title: Impact of fast transient charging and ambient on mobility of WS2 field-effect transistor Authors: Park, Junghak; Woo, Hyunsuk; Jeon, Sanghun Abstract: The authors present the impact of fast charging and the ambient on the intrinsic mobility of a WS2 field-effect transistor (FET) by fast pulsed current-voltage (I-V) measurement. Conventional electrical analysis using the direct current (DC) I-V method in air causes charge trapping during measurement, making it impossible to determine the intrinsic device characteristics. Thus, the authors employed the fast pulsed I-V method in vacuum to minimize fast transient charging and interfacial redox-induced charging during measurement. The authors obtained field-effect mobility values of 16.27 and 14.92 cm(2)/V s in vacuum and air, respectively, using the fast I-V technique; these mobility values were 52%-65% higher than those obtained by the DC method in vacuum and air, respectively. The authors also determined the intrinsic mobility of the WS2 FET using the threshold voltage shift with pulse amplitude. (C) 2017 American Vacuum Society.

2017-09-01T00:00:00Z