Fowler-Nordheim tunneling mechanism Graphene/GaN ultraviolet position-sensitive detector with high precision for optoelectronic demodulation applications

As an important component of optical sensors, position-sensitive detector (PSD) plays an important role in non-contact measurement systems and is widely used in many important fields. However, the preparation and application of ultraviolet (UV) PSD are still to be studied. Herein, we propose a high precision UV PSD constructed by graphene (Gr)/GaN heterojunction (active area is 5 ×5 mm2) for the first time, and Fowler-Nordheim tunneling mechanism has been used to improve device performance. Benefiting from the FNT, under a weak light power of 0.06 mW/cm2, the PSD is able to determine the position of the UV light spot through the output photocurrent difference, displays high precision (0.16 μA/mm), excellent weak light detection capability，and good linearity without power supply. Besides, the Gr/GaN show an ultralow threshold voltage (0.132 V) of FNT. When the bias is higher than 0.132 V, photogenerated carriers will tunneling the thin insulation layer by the FNT, resulting in a multiplication of the photocurrent. Therefore, under the same power densities light irradiation (0.06 mW/cm2), the device exhibits an ultrahigh responsivity of 1.88 A/W, a remarkable detectivity of 2.71 × 1013 Jones, and a high LDR of over 99.58 at 0 V bias. More importantly, as an optoelectronic demodulator the device realizes the decoding of optical signals into electrical signals, showing great potential for application in non-contact measurement systems.