Silicon MIS diodes with Cr2O3 nanofilm: Optical, morphological/structural and electronic transport properties

In this work we report the optical, morphological and structural characterization and diode application of Cr₂O₃ nanofilms grown on p-Si substrates by spin coating and annealing process. X-ray diffraction (XRD), non-contact mode atomic force microscopy (NC-AFM), ultraviolet-visible (UV-vis) spectroscopy and photoluminescence (PL) spectroscopy were used for characterization of nanofilms. For Cr₂O₃ nanofilms, the average particle size determined from XRD and NC-AFM measurements was approximately 70 nm. Structure analyses of nanofilms demonstrate that the single phase Cr₂O₃ on silicon substrate is of high a crystalline structure with a dominant in hexagonal (1 1 0) orientation. The morphologic analysis of the films indicates that the films formed from hexagonal nanoparticles are with low roughness and uniform. UV-vis absorption measurements indicate that the band gap of the Cr₂O₃ film is 3.08 eV. The PL measurement shows that the Cr₂O₃ nanofilm has a strong and narrow ultraviolet emission, which facilitates potential applications in future photoelectric nanodevices. Au/Cr₂O₃/p-Si metal/interlayer/semiconductor (MIS) diodes were fabricated for investigation of the electronic properties such as current-voltage and capacitance-voltage. Ideality factor and barrier height for Au//Cr₂O₃/p-Si diode were calculated as 2.15 eV and 0.74 eV, respectively. Also, interfacial state properties of the MIS diode were determined. The interface-state density of the MIS diode was found to vary from 2.90 × 10¹³ eV⁻¹ cm⁻² to 8.45 × 10¹² eV⁻¹ cm⁻².