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.