Effect of Cu2O Sputtering Power Variation on the Characteristics of Radio Frequency Sputtered p-Type Delafossite CuCrO2 Thin Films

Abstract

For the first time, the effect of Cuprous Oxide (Cu2O) sputtering power variation on the radio frequency sputtered Copper Chromium Oxide (CuCrO2) thin films was studied. In this work, the sputtering power of Cr2O3 was held constant at 200 W while the sputtering power of the Cu2O target was varied from 10 to 100 W. The films were subsequently annealed at 650 °C in N2 ambiance. The effects of Cu2O sputtering power variation on the structural, optical, and electrical properties of the films have been reported in this work. X-ray diffractometer (XRD) study revealed that the single-phase delafossite structure of CuCrO2 was only obtained at Cu2O sputtering power of 50 W. X-ray photoelectron spectroscopy (XPS) analysis further established the results of XRD study where Cu in 1+ oxidation state was identified in thin films obtained at 50 W of Cu2O sputtering power. The optical studies were conducted in this work on all the post-deposition annealed films in the wavelength range of 200–800 nm. The energy dispersive x-ray spectroscopy (EDS) study revealed a near stoichiometric composition ratio of 1:1.06 of Cu:Cr at% obtained in the films sputtered with 50 W of Cu2O sputtering power. The highest optical transmission of ~81% and the highest optical bandgap of 3.21 eV were observed for single-phase CuCrO2 thin films. The optical transmission and the optical bandgap were found to decrease with an increase in the Cu2O sputtering power. The electrical study performed on all the post-deposition annealed films revealed that the lowest resistivity of 0.652 Ω-cm was identified for single-phase CuCrO2 thin films obtained at 50 W of Cu2O sputtering power.

Deposition and Optical Characterization of Sputter Deposited p-Type Delafossite CuGaO2 Thin Films Using Cu2O and Ga2O3 Targets

“…Extensive research has been conducted on n-type TCOs such as Sn-doped In 2 O 3 (ITO) [9,10], Sc-doped ZnO [11,12], and Al-doped ZnO (AZO) [13][14][15][16]. Nonetheless, there exists a lack of research on p-type TCOs, impeding the progress of transparent electronics applications [17][18][19]. In the case of p-type TCOs, it is difficult to synthesize a film that has both good optical transparency and high electrical conductivity.…”

“…Delafossite compounds incorporating Cu+ cations are referred to as Cu-based delafossites. Copper-based delafossites are gaining a lot of attention due to their large bandgap [19,27]. Cu-based delafossite materials are represented by the chemical formula CuMO 2 , with Cu denoting the positively charged monovalent cation (Cu+), M representing trivalent cations such as Cr 3+ , Ga 3+ , and Y 3+ , and oxygen serving as the negatively charged divalent anion (O 2− ).…”