Low temperature processed highly conducting, transparent, and wide bandgap Gd doped CdO thin films for transparent electronics

R. K. Gupta, Missouri State University
K. Ghosh, Missouri State University
R. Patel, MSU JVIC-CASE
P. K. Kahol, Missouri State University

Abstract

Gadolinium (Gd) doped cadmium oxide (CdO) thin films are grown at low temperature (100 °C) using pulsed laser deposition technique. The effect of oxygen partial pressures on structural, optical, and electrical properties is studied. X-ray diffraction studies reveal that these films are polycrystalline in nature with preferred orientation along (1 1 1) direction. Atomic force microscopy studies show that these films are very smooth with maximum root mean square roughness of 0.77 nm. These films are highly transparent and transparency of the films increases with increase in oxygen partial pressure. We observe an increase in optical bandgap of CdO films by Gd doping. The maximum optical band gap of 3.4 eV is observed for films grown at 1 × 10-5 mbar. The electrical resistivity of the films first decreases and then increases with increase in oxygen partial pressure. The lowest electrical resistivity of 2.71 × 10-5 Ω cm and highest mobility of 258 cm2/Vs is observed. These low temperature processed highly conducting, transparent, and wide bandgap semiconducting films could be used for flexible optoelectronic applications.