Defects assisted visible light sensing in Zn1-x (GaSi) x/2O

Abstract

Hexagonal wurtzite Zn1-x(SiGa)x/2O (x = 0, 0.0156, 0.0234, and 0.0312) with a space group of P63mc was synthesized using the solgel method. Investigations of structural, optoelectronic, and photo-sensing study of these samples were performed. Improved crystallinity of the co-doped samples was observed from structural and vibrational studies. The effect of higher charges Ga3+ and Si4+ on various latent defects of ZnO was studied. A predominantly n-type carrier concentration was noticed in all samples. Enhancement in carrier concentration, mobility, and conductivity was observed in the Ga-Si co-doped samples. In this work, the impact of intrinsic defects on photosensing was also studied. UV (290 nm) and visible lights of different wavelengths, blue (450 nm), green (540 nm), and red (640 nm), were sensed. The sensitivity toward the above-mentioned wavelengths was compared for all the samples. Photocurrent was modified with the illumination wavelengths (290, 450, 540, and 640 nm) and also varied with co-doping. A correlation of structural, defect, and optoelectronic properties was discussed, which revealed improved photo-response currents for UV light and for the blue, green and red lights. It was observed that pure ZnO is more sensitive to UV light. However, higher substitution yields better sensitivity for red light. The same result was found for green and blue light sensing.