Ultraviolet enhanced Si-photodetector using p-NiO films

We report on the properties of a heterojunction photodiode composed of p-type NiO and n-type Si. This photodetector was fabricated by evaporating NiO powders on Si (1 0 0) substrate. Our deposited p-NiO film was found to have a hole concentration of ∼1019 cm−3 according to Hall measurements. Current-voltage (I-V) characteristics of our photodiode were measured in the dark and under ultra-violet (UV)-vis light illuminations (290 nm, 325 nm, 460 nm, 540 nm, and 633 nm) at room temperature (RT). The photo-responsivity of our photodiode appeared almost saturated even at 0 V, showing good photo-voltaic properties. The responsivity was as high as ∼0.36 A/W at 0 V and ∼0.40 A/W at 30 V for visible light (633 nm) while it was 0.15 A/W at 0 V and 0.17 A/W at 30 V for UV (290 nm).