Reactive SputteredWide-Bandgap p-Type Semiconducting Spinel AB2O4 and Delafossite ABO2 Thin Films for “Transparent Electronics”

Abstract

Reactive sputtering is one of the most widely used techniques for preparing compound thin films (such as oxides, nitrides, carbides, etc.) by sputtering metal targets in an active gas atmosphere (Ar + O2/N2/CH4, etc.) [1–4]. In this chapter, we have discussed, in details, the formation of spinel and delafossite materials of the form AB2O4 and ABO2 (A and B may be monovalent, divalent, trivalent, or tetravalent cations, depending on the crystal structure, described later) by reactive sputtering technique. Specially, wide bandgap, ptype semiconducting, and transparent oxide materials with delafossite and spinel structure, having interesting applications in “Transparent Electronics,” have been discussed in details. In Sects. 12.2–12.5, a detailed review on the structural, optical, and electrical properties of these p-type transparent conducting oxides (p-TCOs), deposited by reactive sputtering technique, has been presented and the origin of p-type conductivity of these materials has been discussed with considerable attention. Most of the results presented in these sections are reported by various authors working on this field. In Sect. 12.6, synthesis and electro-optical characterization of one of the very important delafossite, p-type semiconducting, and wide-bandgap material, such as CuAlO2, produced by our group via reactive sputtering technique, have been discussed in details. Detailed discussions on spinel- and delafossitestructured material can be found in various literatures [5–14]. Also, detailed reviews on the p-TCO materials have been published by us and others [15–17], which cover the syntheses and properties of a range of p-TCO materials reported so far.