Dual detection of ultraviolet and visible lights using a DNA-CTMA/GaN photodiode with electrically different polarity

Abstract

We demonstrated the dual-detectable DNA-CTMA/n-GaN photodiode (DG-PD) for ultraviolet and visible lights. Halogen and UV lamps are employed to recognize the visible and UV wavelength, respectively. The DG-PD under dark condition has a negative-bias shift of current-voltage (I-V) curves by 0.78 V compared to reference diode without DNA. However, the I-V curves move towards positive bias side by 0.75 V and 1.02 V for the halogen-and UV-exposed photodiode, respectively. These cause electrically different polarity and amount for halogen-and UVinduced photocurrents, indicating that the DNA-CTMA on n-GaN is quite effective for recognizing visible and UV lights as a dual-detectable photodiode. The formation and charge transport mechanisms are also discussed. (C) 2014 Optical Society of America