High-performing ITO/CuO/n-Si photodetector with ultrafast photoresponse

A thin CuO layer was used as an interfacial layer of the ITO/Si device for the high-performing visible/NIR photodetector. The CuO-embedded photodetector (ITO/CuO/Si) has a higher potential barrier height of 0.5 eV than 0.35 eV of the ITO/Si photodetector. The interlayer of a thin CuO film is effective to reduce the lattice mismatches and trapping sites between the ITO and the Si junction. X-ray diffraction was performed to investigate the quality of the CuO film to show the prominent peaks of (002) and (111) lattice planes, confirming the pure CuO formation. The combination of CuO/ITO transparent layers provided low reflectance of 3% or less in the visible range. Due to the CuO interlayer, decent electrical performances were achieved from the ITO/CuO/Si photodetector with a fast rise time (τr = 34.32 ms) and a fall time (τf = 31.68 ms). The photoresponse ratios of the ITO/CuO/Si photodetector were enhanced by one order higher than those of the ITO/Si photodetector for broad wavelengths. The interlayer of CuO film may provide a route for high-performing photodetectors and solar cells.