Issue 20, 2022

Prediction and realisation of high mobility and degenerate p-type conductivity in CaCuP thin films

Abstract

Phosphides are interesting candidates for hole transport materials and p-type transparent conducting applications, capable of achieving greater valence band dispersion than their oxide counterparts due to the higher lying energy and increased size of the P 3p orbital. After computational identification of the indirect-gap semiconductor CaCuP as a promising candidate, we now report reactive sputter deposition of phase-pure p-type CaCuP thin films. Their intrinsic hole concentration and hole mobility exceed 1 × 1020 cm−3 and 35 cm2 V−1 s−1 at room temperature, respectively. Transport calculations indicate potential for even higher mobilities. Copper vacancies are identified as the main source of conductivity, displaying markedly different behaviour compared to typical p-type transparent conductors, leading to improved electronic properties. The optical transparency of CaCuP films is lower than expected from first principles calculations of phonon-mediated indirect transitions. This discrepancy could be partly attributed to crystalline imperfections within the films, increasing the strength of indirect transitions. We determine the transparent conductor figure of merit of CaCuP films as a function of composition, revealing links between stoichiometry, crystalline quality, and opto-electronic properties. These findings provide a promising initial assessment of the viability of CaCuP as a p-type transparent contact.

Graphical abstract: Prediction and realisation of high mobility and degenerate p-type conductivity in CaCuP thin films

Supplementary files

Article information

Article type
Edge Article
Submitted
16 3 2022
Accepted
26 4 2022
First published
26 4 2022
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2022,13, 5872-5883

Prediction and realisation of high mobility and degenerate p-type conductivity in CaCuP thin films

J. Willis, I. Bravić, R. R. Schnepf, K. N. Heinselman, B. Monserrat, T. Unold, A. Zakutayev, D. O. Scanlon and A. Crovetto, Chem. Sci., 2022, 13, 5872 DOI: 10.1039/D2SC01538B

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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