Material Design of p-Type Transparent Amorphous Semiconductor, Cu–Sn–I

Abstract

Transparent amorphous semiconductors (TAS) that can be fabricated at low temperature are key materials in the practical application of transparent flexible electronics. Although various n-type TAS materials with excellent performance, such as amorphous In-Ga-Zn-O (a-IGZO), are already known, no complementary p-type TAS has been realized to date. Here, a material design concept for p-type TAS materials is proposed utilizing the pseudo s-orbital nature of spatially spreading iodine 5p orbitals and amorphous Sn-containing CuI (a-CuSnI) thin film is reported as an example. The resulting a-CuSnI thin films fabricated by spin coating at low temperature (140 °C) have a smooth surface. The Hall mobility increases with the hole concentration and the largest mobility of ≈9 cm² V⁻¹ s⁻¹ is obtained, which is comparable with that of conventional n-type TAS.

A new design concept for p-type transparent amorphous semiconductor materials is proposed utilizing the extended pseudo s-orbital nature of spatially spread iodine 5p orbitals and an amorphous Sn-containing CuI (a-CuSnI) thin film is specifically reported. The a-CuSnI thin films spin coated at low temperature exhibit flat surfaces and large Hall mobility of 3–9 cm² V⁻¹ s⁻¹, which is comparable with that of conventional n-type transparent amorphous oxide semiconductors.

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