Temperature- and light-sensitive mechanism in metal/organic/n-GaN bio-hybrid temperature photodiode based on salmon DNA biomolecule

Temperature-based organic–inorganic photodiodes have recently become attractive applications in branches of science and technology with eco-friendly and hybrid concepts. Here, we describe the use of salmon DNA (SDNA) biomolecules as temperature and light sensors. We demonstrate the temperature- and light-sensitive mechanism of polarity switching in metal/organic/n-GaN bio-hybrid photodiodes based on salmon DNA-cetyltrimethylammonium chloride (SDNA-surfactant). The SDNA-surfactant/n-GaN bio-hybrid temperature photodiode (Bio-HTPD) shows negative bias shift of current (I)–voltage (V) plots by 0.70 and 0.42 V compared to zero-bias at temperatures of 275 and 300 K, respectively, under light illumination. However, the I–V plots of the Bio-HTPD moved towards positive bias by 0.08 V compared to zero-bias at 325 K under light irradiation. This phenomenon resulted in electrically negative photocurrents up to room temperature, which remarkably switched to positive photocurrents at above room temperature. The temperature variations are closely associated with charge activation and unidirectional transport in the SDNA-surfactant biomolecule. Moreover, the change from negative to positive photocurrent could be related to high electron–hole pair generation at higher transition temperature. The formation of an energy band model with thermal hopping is proposed, which explains the reasonable charge transport mechanism.