Electrical Engineering and Computer Science

Dissertation Defense

Advances in Amorphous Oxide Semiconductor Devices, Materials, and Processes for Customizable Scalable Manufacturing of Thin-Film Electronics

Christopher R. Allemang

Electronic circuits comprised of amorphous oxide semiconductor (AOS) thin-film transistors (TFTs) are essential to modern display technologies because of their reasonably high electron mobility and ease of thin-film preparation. These same characteristics make AOS TFTs an ideal candidate for developing thin-film electronics for beyond-display technologies including monolithic 3D integration on Si CMOS ICs and customizable manufacturing.

In this thesis, we make advances in AOS devices, materials, and processes to enable AOS-based thin-film electronics for beyond-display technologies. First, we develop a low-temperature atomic layer deposition (ALD) process to deposit high-performance amorphous zinc tin oxide (a-ZTO). Through optimization of process conditions, we increase film density, resulting in the highest performance ALD-based ZTO TFTs. Second, by developing a passivation layer for the device back-channel, we improve ambient, temporal, and bias stress stability. Third, through an interdisciplinary collaboration we use electrohydrodynamic-jet (e-jet) printing and area-selective ALD (AS-ALD) of oxide thin-film materials to enable customizable manufacturing of thin-film electronics. We demonstrate the first TFT fabricated using an e-jet/AS-ALD process and identify several pathways to further improve device performance. Finally, I expand the applications of AOS TFTs by demonstrating high-voltage TFTs and investigating Schottky contacts to the AOS films we developed.

Chair: Professor Becky (R.L.) Peterson