Interfacial modification in Si/CdO heterojunction by Ge doping for optoelectronic applications

•Doping of Ge to CdO/Si heterojunction controls its optoelectrical properties.•Utmost optosensitivity (60,000%) was found with 0.16 wt% Ge-doped CdO layer.•Optical response of 319.4 mA/W was recorded for 0.25% Ge-doped CdO.•CdO:Ge/Si heterojunctions act as a promise candidates for high-efficiency photodetectors.

The electrical properties of Ge-doped CdO (CdO:Ge) films grown on p-Si were studied in this work. The focussing was on the effect of optoelectrical properties of CdO:Ge film on the optoelectrical properties of the constructed p–n heterojunction, as well as to study the dependence of the optosensitivity and optoresponse of the heterojunction on the Ge% doping level. The characterisation of the transparent conducting oxide CdO:Ge layer was performed by the X-ray diffraction, SEM, electrical measurements, and spectral photometry. A strong optosensitivity was found especially for the p–n heterojunction that used 0.16 wt% Ge-doped CdO, attaining a great value of about 60,000% comparing to undoped CdO. In addition, a good value of optical response of 319.4 mA/W for the p–n heterojunction constructed with 0.25 wt% Ge-doped CdO. The results show that CdO:Ge/p-Si heterojunctions act as very good candidates for constructing high-efficiency photodetectors.

Graphical abstractThe dependence of the optical sensitivity σSen and response S* (A/W) for the constructed (Au/Ge-doped CdO/n-Si) heterojunction were measured as a function of Ge doping level.Figure optionsDownload full-size imageDownload as PowerPoint slide