Calcium incorporated copper indium oxide thin films - a promising candidate for transparent electronic applications

•Calcium incorporation in n-Copper Indium Oxide (CIO) for inducing p-type conduction.•n-CIO/p-Ca doped CIO homojunctions fabricated show good diode characteristics.•Conductivity mechanisms of Ca-doped CIO at different temperature regimes studied. This paper reports the possibility to fabricate transparent diodes with the configuration: Fluorine doped Tin Oxide/n-type copper indium oxide/p-type calcium doped copper indium oxide/Silver with better rectification ratio than that of the diodes with Sn-doped Copper Indium Oxide as the n-counterpart of p- calcium doped copper indium oxide. The ideality factor and turn on voltage of the former diodes are determined as ~1.1 and ~ 0.68 respectively while for the latter types they are ~2.38 and ~ 0.5 V respectively. In addition to this, the paper details the structural, morphological, optoelectronic and electrical properties of delafossite crystalline p-type calcium doped copper indium oxide thin films deposited by activated reactive evaporation in oxygen plasma followed by post air annealing. The temperature of crystallization of the films obtained here is the lowest crystallization temperature reported for the delafossite formation of this compound till date. Electrical transport mechanisms governing conductivities in the temperature range 55 – 430 K are also investigated.