Low-Intensity UV light sensor based on p-NiO/n-Si heterojunction

We studied the performance of a photodiode UV sensor based on a p-NiO/n-Si heterojunction. NiO thin film was prepared via a two-step process. In the first step, a thin film of Ni metal was evaporated on an n-Si substrate. Subsequently, the sample was thermally oxidized at 500 degrees C for 3 h in an ambient atmosphere. The phases and surface morphology of the prepared sample was determined by using x-ray diffraction analysis and scanning electron microscopy, respectively. The rectifying ratio of the prepared device was approximately 7 at a bias voltage of +/- 10 V, with a barrier height and ideality factor of 0.77 +/- 0.03 eV and 16, respectively. The prepared device was tested for potential applications as a UV sensor. The prepared device exhibits high repeatability and fast response times of 1.5 s and 0.7 s for the rise and full time, respectively. The prepared photodiode responds to low-intensity UV light in the range from 30 mu W.cm(-2) to 430 mu W.cm(-2).