CVD-deposited Cu2O thin films with a record Hall hole mobility of 263 cm2 V−1 s−1 and field-effect mobility of 0.99 cm2 V−1 s−1

Singh, V and Sinha, J and Shivashankar, SA and Avasthi, S (2023) CVD-deposited Cu2O thin films with a record Hall hole mobility of 263 cm2 V−1 s−1 and field-effect mobility of 0.99 cm2 V−1 s−1. In: Journal of Materials Chemistry C, 11 (22). pp. 7356-7366.

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Abstract

Cuprous oxide (Cu2O) is one of the few p-type semiconductor oxides that allow hole transport, making it useful for a variety of electronic applications, such as p-channel thin-film transistors (TFTs). Unfortunately, unlike n-type oxides, the performance of p-type oxide TFTs is poor. Even though Cu2O has a reported bulk hole mobility of ∼250 cm2 V−1 s−1, the best TFT mobility is 100-fold lower. In addition, the record performance has not been improved since 2009. This work shows a rational path to obtain a record hole mobility in Cu2O films and devices. Using chemical vapor deposition, instead of the more commonly used physical vapor deposition method, precise control over the deposited film's nucleation rate and grain size is enabled. The grain size can be increased further by tuning the surface energy of the growth surface. These optimizations enable us to improve the bulk hole mobility from 53 to 263 cm2 V−1 s−1, which is the highest mobility reported in Cu2O thin films. We demonstrate p-channel thin-film transistors on four different dielectrics in the bottom-gate configuration, and we show that unpassivated bonds on the dielectric surface are the reason for the much smaller field effect mobility in Cu2O thin films. The best TFT delivers a hole mobility of 0.99 cm2 V−1 s−1, which is one of the highest values reported in the recent literature. More importantly, the results are repeatable and consistent in the mobility, subthreshold swing, and threshold voltage. Bias-stress studies show that the I-V characteristics show minimal drift, even after 1500 s of stress. The work is a significant advance for state-of-the-art p-type all-oxide electronics.

Item Type:	Journal Article
Publication:	Journal of Materials Chemistry C
Publisher:	Royal Society of Chemistry
Additional Information:	The copyright for this article belongs to the Royal Society of Chemistry
Keywords:	Chemical vapor deposition; Dielectric materials; Grain size and shape; Hall mobility; Physical vapor deposition; Thin film circuits; Thin film transistors; Thin films; Threshold voltage, C. thin film transistor (TFT); Electronics applications; Field-effect mobilities; Grainsize; Hole transports; P channels; P type semiconductor; Performance; Semiconductor oxides; Thin-films, Hole mobility
Department/Centre:	Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering
Date Deposited:	09 Jul 2023 17:35
Last Modified:	09 Jul 2023 17:35
URI:	https://eprints.iisc.ac.in/id/eprint/82099

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