Solution-Processed Aluminum-Zirconium Oxide as a Gate Dielectric for InGaZnO Thin Film Transistors

• Published in: Journal of electrical engineering & technology Vol. 19; no. 1; pp. 567 - 575
• Main Authors: Han, Jeong Hun, Lee, So Young, Kim, Hyo Eun, Jeon, Jae-Hong, Park, KeeChan, Moon, Kook Chul, Im, Hwarim, Kim, Yong-Sang
• Format: Journal Article
• Language: English
• Published: Singapore Springer Nature Singapore 2024; 대한전기학회
• Subjects: Electrical Engineering; Electrical Machines and Networks; Electronics and Microelectronics; Engineering; Instrumentation; Original Article; Power Electronics; 전기공학; Indium–gallium–zinc oxide; Aluminum–zirconium oxide; Thin-film transistors; Hysteresis; Solution process
• ISSN: 1975-0102; 2093-7423
• DOI: 10.1007/s42835-023-01696-5

This study presents a solution-processed aluminum-zirconium oxide (AlZrO x ) dielectric for amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs). Solution-processed AlZrO x thin films exhibit overall improved dielectric properties, such as leakage current characteristics of 1.10 × 10 –8  A/cm 2 at 0.5 MV/cm and high dielectric constants of approximately 9.1 by combining the advantages of aluminum oxide (AlO x ) and zirconium oxide (ZrO x ). Solution-processed IGZO TFTs using the AlZrO x film as a gate insulator layer exhibited a threshold voltage of 0.64 V, field-effect mobility of 3.06 cm 2 /V s, and a subthreshold slope of 0.26 V/dec. In addition, the IGZO TFTs with the AlZrO x films exhibited a higher on/off current ratio of 1.05 × 10 6 than devices with the AlO x and ZrO x gate insulator layers. The improvement of device properties is mainly attributed to the interface properties. The IGZO TFTs with the AlZrO x gate insulator exhibited the lowest interface trap density of 2.07 × 10 12  cm −2  eV −1 , compared to the devices with the AlO x and ZrO x gate insulators of 3.30 × 10 12 and 5.06 × 10 12  cm −2  eV −1 , respectively, because of the smooth surface roughness and reduced residual hydroxyl groups in the films. The IGZO TFTs with the AlZrO x gate insulator also improved hysteresis characteristics with the hysteresis window of 0.17 V. This study presents a significant step toward developing low-cost, low-power-consumption, and high-performance oxide electronic device.