Highly-performing Ni/SiO2/Si MIS photodetector for NIR detecting applications

Abstract

The highly sensitive Ni/SiO2/n-Si metal–insulator–semiconductor (MIS) photodetector was fabricated using DC sputtering method for NIR applications. A thin insulating SiO2 layer was formed in between Si and Ni to enhance the electrical properties of the device. The transmittance of the top Ni layer was modified by adjusting the O2 flow into the sputtering chamber and it showed the maximum transmittance of 90.14% for broad wavelength range of 400–1100nm. The presence of Si, O, Ni and Al elements in the Ni/SiO2/n-Si photodetector were confirmed from EDX spectrum. The SiO2 layer increased the built-in potential to give rise to the forward current of 50mA. As the prepared MIS photodetector possessed the improved barrier height of 0.75eV, it showed the high rectification ratio of 19,560. The ideality factor of the prepared MIS detector was obtained as 1.14. The barrier height and ideality factor of the presented device were higher when compared to the previously reported values. The photoresponse of the device was gradually increased and yielded the maximum response at λ=900nm with the high response ratio of 3480. We demonstrated that the highly sensitive photodetection for long wavelengths can be realized by designing of MIS structures.