Hot Carrier-Assisted Performance Enhancement in ZnO-Based UV Photodetectors Using Plasmonic Au Nanoparticles

This study demonstrates a notable improvement in ultraviolet (UV) photodetector (PD) performance through the integration of gold nanoparticles (Au NPs) on a 3 M ZnO thin film (TF). The Au NPs induce a localized surface plasmon resonance (LSPR) effect, which enhances light absorption and promotes efficient charge carrier generation. The device, configured in an Ag/Au:ZnO/Ag metal-semiconductor-metal (MSM) structure, exhibited a remarkable enhancement in responsivity, increasing from 43 A/W (pristine ZnO) to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.8~\boldsymbol {\times } 10^{{3}}$</tex-math> </inline-formula> A/W, along with a sensitivity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.7~\boldsymbol {\times } 10^{{6}}$</tex-math> </inline-formula>. This performance boost is attributed to plasmon-induced hot carrier injection and localized near-field enhancement. In addition, the device achieved a specific detectivity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\boldsymbol {\sim }\!\!1~\boldsymbol {\times } 10^{{15}}$</tex-math> </inline-formula> Jones, an external quantum efficiency (EQE) of 7% <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\boldsymbol {\times } 10^{{5}}$</tex-math> </inline-formula>%, and a linear dynamic range (LDR) of 124 dB (at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\boldsymbol {\lambda }_{\text {ex}} =330$</tex-math> </inline-formula> nm). These results demonstrate the potential of plasmonic nanostructures (NSs) in driving next-generation, high-efficiency UV PDs based on solution-processed ZnO films.