The effective role of potassium doping in improving the structural, morphological optical, and electrical properties of CdO thin film for optoelectronic application

Aspiring to increase the electrical conductivity, enhance the electron mobility, and widen the band gap, potassium (K) was used as a substitutional dopant in the CdO matrix. Transparent cadmium oxide (CdO) and potassium-doped cadmium oxide (K-CdO) thin films with different K concentrations (0.02, 0.04, and 0.06 mol) were deposited on glass substrates via thermal evaporation technique. A remarkable shift of (111) peak towards high Bragg's angle was noticed as the potassium content was increased, which established the successful incorporation of K into the CdO matrix. The surface became more compacted and denser with a noticeably smaller particle size upon doping with K, as revealed by field emission scanning electron microscopy (FESEM) aand the Willmason-Hall plot. The optical band gap was boosted from 2.5 to 2.79 eV, when the K concentration was increased from 0.0 to 0.06 mol. Moreover, the optoelectronic features, such as transmittance, reflectance, skin depth, refractive index, tailing energy, optical dielectric constants, and optical conductivity were investigated in depth. The Hall experiment was used to determine the DC electrical properties of the K- CdO film including the resistivity (rho), Carrier concentration, Carrier mobility, and Hall coefficient. The Hall measurement asserted that the film is an n-type semiconductor and electron mobility (mu n) was boosted, as the K concentration was raised. The increased optical band gap and enhanced electron mobility achieved by potassium doping reflected the fact that K-doped CdO thin films are promising window layers in photovoltaic applications.