Effect of illumination and frequency dependent series resistance and interface state densities on the electrical properties of DNA-CTMA/p-GaN bio-hybrid Schottky photodiode

A deoxyribonucleic acid-cetyltrimethylammonium chloride (DNA-CTMA) biopolymer-based inorganic p-type GaN bio-hybrid Schottky photodiode was fabricated and its electrical characteristics were studied. The Al/Cr/DNA-CTMA/p-GaN bio-hybrid photodiode parameters were investigated using current-voltage (I-V), capacitance-voltage-frequency (C-V-f) and conductance-voltage-frequency (G/ω-V-f) measurements. The calculated ideality factor and barrier height of the diode were found to be 1.8 and 0.82 eV, respectively. The electrical and photo-conduction properties of the diode were examined using dark I-V and steady-state photoconductivity techniques. The C-V-f and G/ω-V-f measurements showed that the capacitance and conductance of the diode depends on the bias voltage and frequency, respectively. On the other hand, a decrease in capacitance and increase in conductance with increasing frequency at room temperature were demonstrated based on the interface state density. In addition, the interface state density decreased exponentially with increasing frequency. It is also noted that series resistance decreased with increasing frequency. The results showed that the biopolymer-based Al/Cr/DNA-CTMA/p-GaN bio-hybrid photodiode can be used as a photosensor in optical applications and the development of high-performance organic-inorganic-based p-Schottky diodes that are environmentally safe.