A Site‐Specific Charge Carrier Control in Monolithic Integrated Amorphous Oxide Semiconductors and Circuits with Locally Induced Optical‐Doping Process

• Published in: Advanced functional materials Vol. 29; no. 39
• Main Authors: Kim, Kyung‐Tae, Jeon, Seong‐Pil, Lee, Woobin, Jo, Jeong‐Wan, Heo, Jae Sang, Kim, Insoo, Kim, Yong‐Hoon, Park, Sung Kyu
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01.09.2019
• Subjects: amorphous oxide semiconductors; Amorphous semiconductors; Analog circuits; complementary amplifier; controllable threshold voltage; Current carriers; Digital signal processing; Doping; Gallium; Indium gallium zinc oxide; Integrated circuits; Materials science; optical‐doping; Optimization; Oscillators; Parameters; photochemical activation; Production costs; Semiconductor devices; Silicon substrates; Single wall carbon nanotubes; Stability; Thin film transistors; Threshold voltage; Zinc oxide
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201904770

Amorphous oxide semiconductor (AOS) thin film transistors (TFTs) have found cutting‐edge applications in sensor technologies. To reduce manufacturing costs, sensors, analog front end, and digital signal processing circuits need to be integrated on the identical substrate. Unlike traditional silicon‐based devices, optimizations for locally controllable electrical parameters of the AOSs have rarely been investigated. Here, photoactivated combustion reduction is utilized as doping motivation for solution‐processed amorphous indium–gallium–zinc oxide (a‐IGZO) to tune their electrical performance. By controlling parameters of a‐IGZO TFTs, which can be partly doped with covering the desired area of the identical substrate, it is possible to match the particular threshold voltage for various circuits. For circuit optimization, automatic integrated circuit modeling spice is carried out to find the best match of the complementary metal–oxide semiconductor circuits. Finally, the site‐specific performance of switching TFTs, amplifiers, and ring oscillators implemented with low‐temperature solution‐processed a‐IGZO and p‐type single‐walled carbon nanotube TFTs is demonstrated. The optical‐doped a‐IGZO TFTs exhibiting a saturation mobility of >9.15 cm2 V−1 s−1 with a locally tunable threshold voltage of −5 – 1.5 V are realized, enabling monolithic integration of functional devices. The resultant circuits demonstrate excellent amplification of 24 dB and an oscillation frequency of 12 kHz for 7‐stage ring oscillators. A facile site‐specific optical‐doping process is realized to locally control the charge carrier concentration of low‐temperature solution‐processed a‐IGZO thin films. It can be used as a general route to fabricate practical on‐chip applications implemented with diverse optimized amorphous oxide semiconductor devices such as switching thin film transistors, analogue amplifiers, and digital ring oscillators.