Silver Nanowire-Based Infrared-Transparent Contacts for Future High-Density Format Focal Plane Arrays

We report the first demonstration of: 1) wide-wavelength range, infrared transparent conductors (ITCs) made of silver nanowires (Ag NWs), and 2) ITC contact-integrated prototype, InAsSb midwavelength IR (MWIR) detectors. The Ag NW-based ITCs show optical transmittance (T_λ) of ,,94% in the 0.9-2.5 μm wavelength range with a sheet resistance (R_s) of 19.1 Ω/□. T_λ of the Ag NW-ITC decreases slowly with increasing wavelength, resulting in T_λ ,,92%-87% at 2.5- 8 μm (MWIR) and T_λ ,,87%-82% at 8-15 μm (LWIR). The Ag NWbased ITC makes good ohmic contacts on InAsSb-based MWIR detectors with contact resistance of <;0.5 Ω · mm. The ITC contact-integrated prototype InAsSb IR detectors are front-side illuminated and show external quantum efficiency (QE) of >85% at 4.25 μm and 150K. The measured external QE remains at the same high level regardless of detector fill factor. These results indicate that Ag NW-ITCs may enable future pixel scaling for front-side illuminated, high-density-format focal plane arrays without compromising QE, responsivity, and detector performance.