CAREER: Fundamental Electronic Device Performance and Reliability Investigation on Chalcogenide- and Oxide-based N- and P-type Materials for Large Area/Flexible Electronics

University Of Texas At Dallas, Richardson TX

Investigators

Abstract

Large area/flexible electronics presents new opportunities for applications benefiting society, such as low- cost, flexible and self-powered sensors, wearable, and even biocompatible electronics. These systems may include "smart" medical bandages that monitor the healing of wounds and medical triage patches that monitor vital signs. Also, light-weight and rugged flexible decals are a potential application for inventory tracking, pollution monitoring, structural reliability of buildings/bridges in urban areas, etc. Currently, a typical fabrication approach to enable circuitry for these applications will use organic materials in a complex integration scheme with inorganic materials "hybrid approach" that will be more costly compared to the proposed work. In addition, a serious limitation of the hybrid approach is device and circuit performance limitations due to exposure of organics to the ambient. To enable high performance systems applications for large area electronics such as "smart" bio monitoring patches, flexible sensors, RFIDs, and microcontrollers, the incorporation of low cost, non-silicon thin-film transistor materials compatible with mechanically flexible properties is essential. Moreover, the flexible application requires substrates processed at relatively low temperatures (< 180°C) compared to conventional silicon-based chip manufacturing. To address this performance gap at low cost, this research proposes exploring an entirely inorganic, non-hybrid semiconductor technology using chalcogenides (sulfur- and tellurium-based materials) and oxides (zinc oxide-based, nickel oxide and tin oxide materials). Using these semiconducting materials will result in a revolution of large-area/flexible electronics by enabling straightforward integration of multiple components (i.e., energy storage/harvesting, displays, and sensors) on a single substrate. Furthermore, they will have a resounding impact on the Internet of Things, medical, defense, and sensors by enabling technologies where it may not be practical and cost effective for silicon. Finally, the education/outreach objectives include engaging with middle school STEM educators for on-campus research in the PI"s lab and incorporating the experience into innovative curriculum plans to take back to their students. In addition, there will be implementation of "units of learning" that incorporate large-area/flex technology into advanced-level courses while also providing undergraduate research opportunities. The objective of this proposal is to fundamentally explore the use of inorganic, low temperature (< 180ºC) chalcogenide- and oxide-based n-type and p-type thin-film semiconductors for low-cost, large-area/flex- compatible devices and circuits. The research plan consists of four (4) phases: (I) materials evaluation; (II) device fabrication; (III) device characterization; and (IV) device simulation/modeling. Using physical and electrical characterization along with modeling/simulation, a comprehensive investigation will provide fundamental device performance and reliability understanding. This work will provide the opportunity to have Cd- and Pb-free materials for p- and n-type semiconductors with high carrier mobility and electrical stability for implantable or wearable electronics. Furthermore, the demonstration of large-area/flex- compatible p/n junctions, junction field effect transistors, and thin-film transistors will truly take large- area/flex processing to new heights and permit complementary circuit capabilities, such as thin film amplifiers and logic circuitry, that have not been demonstrated using appropriate processing conditions (i.e., low temp) for integration into sensors, smart bandages, detectors, RFIDs, etc. This work addresses current challenges in large-area/flex-compatible circuitry where all-inorganic, n- and p-type semiconductor devices, and circuits are vital because an organic-only or a partially organic hybrid approach has more pronounced long-term degradation of organic-based devices. Therefore, inorganic materials and devices are preferred in order to create the needed circuitry. Using these semiconducting materials will result in a revolution of large-area and flexible electronics by enabling straightforward integration of multiple components such as energy storage/harvesting, displays, and sensors on a single substrate. Furthermore, they will have a resounding impact on the Internet of Things, medical, defense, and sensors by enabling technologies where it may not be practical and cost effective for silicon.