Poul Raj, I.L.P.Chidhambaram, N.Saravanakumar, S.Sasikumar, S.Varadharajaperumal, S.Alagarasan, D.Alshahrani, T.Shkir, M.AlFaify, S.2026-02-052021Optik, 2021, 241, , pp. -304026https://doi.org/10.1016/j.ijleo.2021.166406https://idr.nitk.ac.in/handle/123456789/23111The present investigation reports the synthesis of CdO using the facile sol-gel technique. The CdO samples exhibit cubic structure and their crystalline quality increases with different sintering temperatures (550, 650, and 750 °C). The maximum entropy method (MEM) was applied to calculate the charge density distribution of the CdO samples and the two-dimensional charge density maps showed a slight enlargement in the cell volume of the CdO with sintering temperatures. The bandgap of the CdO samples varied from 2.89 to 2.66 eV with increasing sintering temperature. Heterojunction n-CdO/p-Si photodiodes were constructed (using CdO samples) on silicon wafers using the spin coating procedure. The ideality factor of the diodes is found to decrease from 5.2 to 4.2 with sintering temperatures of the CdO. The heterojunction diode constructed using the CdO sample sintered at 750 °C exhibited the highest responsivity and external quantum efficiency values of 0.34 A/W and 109 %, respectively. Improved crystallinity, responsivity, and quantum efficiency make the developed CdO device useful for optoelectronics. © 2021 Elsevier GmbHCadmium compoundsCrystallinityHeterojunctionsMaximum entropy methodsPhotodiodesPolycrystalline materialsQuantum efficiencySemiconductor dopingSilicon compoundsCubic structureEffect of annealingExternal quantum efficiencyMaximum-entropy methodsN-CdO/p-si photodiodePhoto detectionResponsivitySi photodiodesSintering temperaturesSol-gel techniqueRietveld refinement