Enhanced photoresponse performance in GaN based symmetric type MSM ultraviolet-A and MIS ultraviolet-A to C photodetectors

To realize an improved sustainable future, additional developments in the energy consumption is a prerequisite important aspect for the operation of any electronic device. This is correspondingly true and intended for all the commercially existing photodetectors (PDs) which functions using large external bias. So far, thin films have been commonly used in the photodetection of several bands of electromagnetic spectrum. Recently, rare earth oxides have received tremendous attention as a gate dielectric in the photodetection filed on account of their superior characteristics such as large bandgap, high dielectric constant accompanied by thermodynamical stability. Besides, the earlier reported GaN PDs mostly functioned in UV-A region only and there are no pertinent reports pointed at the deep UV region. In this manuscript, we have fabricated and reported Au/GaN MSM UV-A (300–400 nm) and Au/Nd2O3/GaN MIS UV-A to C/VIS (200–600 nm) BB PDs using cost-effective electron beam evaporation technique at room temperature. The reported Au/Nd2O3/GaN MIS BB PD device is sensitive to wavelengths of light from 200 nm to 600 nm (UV to VIS region). This improvement is correlated with the intentionally deposited Nd2O3 visible light absorber thin film at the Au/GaN interface as evidenced from the optical absorption study. The direct optical bandgap, crystal structure, chemical composition/oxidation states and surface morphology of the Nd2O3 material deposited on GaN were demonstrated using UV-Visible, XRD, XPS and AFM techniques. The Au/Nd2O3/GaN MIS BB PD device exhibited an outstanding photodetection performance with maximum photoresponsivity of 6382 mA/W, detectivity of 9.4 × 1014 Jones, external quantum efficiency of 3.67 × 103% and response speed of 770 ms/2320 ms (τFall/τrise) compared to Au/GaN MSM PD device. Thus, these results suggest that the Au/Nd2O3/GaN MIS type BB PD device structure could be employed as a potential candidate to tune the wavelength selectivity from UV to VIS region of the electromagnetic spectrum in the future.