Solution-processed Amorphous Oxide Semiconductors for Thin-film Power Management Circuitry
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The key strengths of thin-film electronics over wafer-based electronics are (i) they can be deposited on various substrates at a large-area scale, and (ii) they can be additively deposited on existing device layers without degrading them. These advantageous features can be used to overcome the current barriers facing silicon (Si) electronics. Among thin-film materials, amorphous oxide semiconductor (AOS) is an attractive candidate due to its high carrier mobility, wide band-gap, and in-air deposition capability.
In this thesis, we push the boundaries of AOS, first by developing an air-stable, ink-based deposition process for high-performance amorphous zinc-tin-oxide semiconductor. Second, by exploiting in situ chemical evolution at the interface of zinc-tin-oxide and various metal electrodes, we intentionally manipulate the electrode contact properties to form high-quality ohmic contacts and Schottky barriers. Third, we combine these techniques to fabricate novel devices, namely vertically-conducting thin-film diodes and Schottky-gated TFTs. Finally, we demonstrate the use of these devices in several novel thin-film power electronics applications. These include thin-film energy harvesters to reduce the current RFID tag cost based on Si IC, thin-film heterointegrated 3D-IC on Si chip for efficient voltage bridging, and thin-film bypass diodes for future integration on solar cells to manage partial shading conditions.