Near-infrared photodetectors based on unique Fe2O3 nanorod array with multi-photon excitation

Due to wide applications in imaging and optical communications, how to develop novel high quality and low-cost candidate materials for near-infrared (NIR) photodetectors has become a hot research topic in recent years. Here, the self-powered NIR photodetector based on novel diamond randomly staggered α-Fe2O3 nanorod array is reported, which exhibits a dark current of 1.0 nA and photocurrent of 0.85 μA at 1.8 W @ 1 V, 40 ℃ with an NIR light irradiation on the novel α-Fe2O3 film. The experimental curve of photocurrent with light intensity is fitted based on equation of Iph= C1Pα, and the exponent α is estimated to have a value of 4.0, implying that there exists a four-photon excitation process under irradiation with wavelength of 808 nm. Furthermore, the J-V characteristics at different substrate temperatures are investigated, and the Arrhenius plot of current density vs temperature shows that the activation energy is about 0.58 eV under dark, but is reduced to 0.32 eV under NIR illumination. Above characteristic of the obtained high NIR photoelectric response can be probably attributed to the synergetic effect of strong light absorption and oxygen vacancies.