Fig. 1. Schematic of (a) proposed and (b) conventional PtSi SBD structure.

Fig. 2. (a) Real and (b) imaginary components of complex permittivity of ZnO:Al material with different electron concentrations.

Fig. 3. Quality factors versus wavelength for ZnO:Al, silver, and gold materials. Inset of the figure shows the εi of ZnO:Al, silver, and gold materials. Note: ZnO:Al can exhibit absorption losses tens or hundreds of times lower than those of silver and gold.

Fig. 4. Absorption efficiency for (a) different ZnO:Al nanoparticle radii r with the distance between the nanoparticles and the PtSi layer p=0.4  μm, and for (b) different p with r=0.65  μm.

Fig. 5. Simulated electric field distributions around nanoparticles at the two peak wavelengths of (a) 3.5 and (b) 4.6 μm in Fig. 4(a), with r=0.65 μm and p=0.4 μm, respectively.

Fig. 6. Absorption efficiencies of conventional SBD structures with and without nanoparticles, and that of the proposed structure.

Fig. 7. Theoretical EQE by our proposed structure compared to the conventional structure. The EQEs of the measurements from the literature and the theoretical limit (A(λ)=1) are also shown.