UV electromagnetic irradiation sensing by GQDs sensitized ZnO/GaN heterostructure for wearable dosimetry

Abstract

Sensing of Ultraviolet (UV) Electromagnetic Irradiations (EIs) for wearable dosimetry is promulgated universally by reserving their place in precise calibration for the controlled exposure of UV-EIs for the betterment of humankind. In other words, the controlled exposure of incident optical power density (OPD) of UV-EIs found advantageous and numerous noble healthcare applications such as beta-endorphin molecule (provide feel-good factor to the brain) level augmentation, adequate vitamin D (physical strength) level formation, in skin treatment like eczema and dermatitis, sensing important biomolecules like Uric Acid (responsible for critical disease related with kidney and heart). Moreover, the controlled exposure of OPDs also significantly impacts UV disinfection technologies, which provide a defensive shield against critical respiratory syndrome coronavirus 2 (SARS-CoV-2), which belongs to the COVID-19 pandemic. Therefore, by understanding the importance of limited exposure to these vital UV-EIs, the present study showcased the GQDs-sensitized ZnO/GaN heterostructured UV sensor utilized to explore the impact of UV-EIs OPDs on their performance. This study helps to develop and utilize the UV sensor-based wearable dosimetry for in-house diagnostics of critical healthcare parameters. This report also divulged an interesting core mechanism (band bending, tunneling through narrowed hole injection under increased negative bias) involved in affecting the performance of the UV-EIs sensor by a function of growing OPDs with the help of a suitable band diagram. The impact of increasing OPDs on fabricated UV-EIs sensors can be well understood by the fact that, by varying the OPDs up to ∼550%, the Gain (G), responsivity (R), external quantum efficiency (EQE) and noise equivalent power (NEP) significantly increases up to (156.7 to 332.4) ∼300%, (118 A W ^−1 to 3200 A W ^−1 ) 2700%, (∼870% to 12 × 10 ^3 %) 1400% and (1.3 pWHz ^−1/2 to 50 fWHz ^−1/2 ) 10,000% respectively at an applied bias of −6 V. Furthermore, the time-correlated transient photoresponse is also dramatically improved with increasing OPDs, wherein the increment in rise and decay time is estimated as (159 ms to 7.86 ms) ∼2000% and (68.7 ms to 12.4 ms) ∼500%, respectively.

Keywords

• GQDs
• ZnO
• GaN
• nanostructures
• optical power density
• ultraviolet irradiations