Persistent photocurrent and deep level traps in PLD-grown In-Ga-Zn-O thin films studied by thermally stimulated current spectroscopy

Buguo Wang; Jason Anders; Kevin Leedy; Michael Schuette; David Look

doi:10.1117/12.2290625

23 February 2018 Persistent photocurrent and deep level traps in PLD-grown In-Ga-Zn-O thin films studied by thermally stimulated current spectroscopy

Buguo Wang, Jason Anders, Kevin Leedy, Michael Schuette, David Look

Author Affiliations +

Proceedings Volume 10533, Oxide-based Materials and Devices IX; 1053314 (2018) https://doi.org/10.1117/12.2290625
Event: SPIE OPTO, 2018, San Francisco, California, United States

Abstract

InGaZnO (IGZO) is a promising semiconductor material for thin-film transistors (TFTs) used in DC and RF switching applications, especially since it can be grown at low temperatures on a wide variety of substrates. Enhancement-mode TFTs based on IGZO thin films grown by pulsed laser deposition (PLD) have been recently fabricated and these transistors show excellent performance; however, compositional variations and defects can adversely affect film quality, especially in regard to electrical properties. In this study, we use thermally stimulated current (TSC) spectroscopy to characterize the electrical properties and the deep traps in PLD-grown IGZO thin films. It was found that the as-grown sample has a DC activation energy of 0.62 eV, and two major traps with activation energies at ~ 0.16-0.26 eV and at ~ 0.90 eV. However, a strong persistent photocurrent (PPC) sometimes exists in the as-grown sample, so we carry out post-growth annealing in an attempt to mitigate the effect. It was found that annealing in argon increases the conduction, produces more PPC and also makes more traps observable. Annealing in air makes the film more resistive, and removes PPC and all traps but one. This work demonstrates that current-based trap emission, such as that associated with the TSC, can effectively reveal electronic defects in highlyresistive semiconductor materials, especially those are not amenable to capacitance-based techniques, such as deeplevel transient spectroscopy (DLTS).

Citation Download Citation

Buguo Wang, Jason Anders, Kevin Leedy, Michael Schuette, and David Look "Persistent photocurrent and deep level traps in PLD-grown In-Ga-Zn-O thin films studied by thermally stimulated current spectroscopy", Proc. SPIE 10533, Oxide-based Materials and Devices IX, 1053314 (23 February 2018); https://doi.org/10.1117/12.2290625

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