Simulation and Analysis of Plasmonic Photodetector Based on Au Nanoparticles and HfO2 Interlayer With Improved Performance in Visible Spectral Region

This work reports on a photodetector (PD) based on SiO2 substrate, Au nanoparticles (NPs), and hafnium oxide (HfO2)/aluminum oxide (Al2O3) interlayer with plasmonic enhancement of light absorption in visible spectral region. Finite difference time domain (FDTD) methodology is used for simulation. The results show that a surrounding medium with higher refractive index (RI) leads to greater absorption with plasmonic enhancement. A thin HfO2 layer (1–2 nm) further increases the light absorption leading to higher magnitudes of quantum efficiency ( $\eta $ ) and responsivity ( $\rho $ ). Additionally, this HfO2 layer causes the operating wavelength ( $\lambda _{{0}}$ , related to peak absorption magnitude “ ${A}$ ”) to considerably red-shift leading to decrease in the scattering ( $\Lambda $ = 1/ $\lambda _{{0}}^{{4}}$ ) of incident light. HfO2-based PD design operating at 594.67 nm provides the values of $\eta $ and $\rho $ as large as 0.498 and 0.239 A/W, respectively, with $\Lambda $ as small as $7.99\,\,\mu \text{m}^{-{4}}$ . Furthermore, a possible practical implementation of the HfO2-assisted PD design is reported while analyzing it with Au electrodes and 10-nm-thick zinc oxide (ZnO) layer. This analysis comprises of dark current ( ${I}_{\text {dark}}$ ) estimation followed by detectivity ( ${D}$ ) evaluation. SiO2–HfO2 (1 nm)–ZnO (10 nm)–Au NP (6 nm radius) structure (with surrounding medium RI = 1.33) achieves that the values of ${A}$ , $\lambda _{{0}}$ , $\eta $ , $\rho $ , $\Lambda $ , ${I}_{\text {dark}}$ , and ${D}$ are 0.312 a.u., 587.96 nm, 0.476, 0.225 A/W, $8.367 ~\mu \text{m}^{\mathbf {-4}}$ , $3.6\times 10^{-{16}}$ A, and $1.48\times 10^{12}$ Jones, respectively. Furthermore, the proposed PD design is able to provide superior performance (i.e., small ${I}_{\text {dark}}$ and $\Lambda $ along with large values of ${D}$ and $\rho $ ) compared to recently reported PD designs.