Search for: All records

Optoelectronic devices in the mid-infrared have attracted significant interest due to numerous potential applications in communications and sensing. Molecular beam epitaxial (MBE) growth of highly doped InAs has emerged as a promising “designer metal” platform for the plasmonic enhancement of mid-infrared devices. However, while typical plasmonic materials can be patterned to engineer strong localized resonances, the lack of lateral control in conventional MBE growth makes it challenging to create similar structures compatible with monolithically grown plasmonic InAs. To this end, we report the growth of highly doped InAs plasmonic ridges for the localized resonant enhancement of mid-IR emitters and absorbers. Furthermore, we demonstrate a method for regaining a planar surface above plasmonic corrugations, creating a pathway to epitaxially integrate these structures into active devices that leverage conventional growth and fabrication techniques. 

Plasmonic materials, and their ability to enable strong concentration of optical fields, have offered a tantalizing foundation for the demonstration of sub-diffraction-limit photonic devices. However, practical and scalable plasmonic optoelectronics for real world applications remain elusive. In this work, we present an infrared photodetector leveraging a device architecture consisting of a “designer” epitaxial plasmonic metal integrated with a quantum-engineered detector structure, all in a mature III-V semiconductor material system. Incident light is coupled into surface plasmon-polariton modes at the detector/designer metal interface, and the strong confinement of these modes allows for a sub-diffractive ($\sim <\#comment/>{\mathrm{\lambda <\#comment/>}}_0/33$) detector absorber layer thickness, effectively decoupling the detector’s absorption efficiency and dark current. We demonstrate high-performance detectors operating at non-cryogenic temperatures ($T=195\mathrm{K}$), without sacrificing external quantum efficiency, and superior to well-established and commercially available detectors. This work provides a practical and scalable plasmonic optoelectronic device architecture with real world mid-infrared applications.

 

Infrared detectors using monolithically integrated doped semiconductor “designer metals” are proposed and experimentally demonstrated. We leverage the “designer metal” groundplanes to form resonant cavities with enhanced absorption tuned across the long-wave infrared (LWIR). Detectors are designed with two target absorption enhancement wavelengths: 8 and 10 μm. The core of our detectors are quantum-engineered LWIR type-II superlattice p-i-n detectors with total thicknesses of only 1.42 and 1.80 μm for the 8 and 10 μm absorption enhancement devices, respectively. Our 8 and 10 μm structures show peak external quantum efficiencies of 45 and 27%, which are 4.5× and 2.7× enhanced, respectively, compared to control structures. We demonstrate the clear advantages of this detector architecture, both in terms of ease of growth/fabrication and enhanced device performance. The proposed architecture is absorber- and device-structure agnostic, much thinner than state-of-the-art LWIR T2SLs, and offers the opportunity for the integration of low dark current LWIR detector architectures for significant enhancement of IR detectivity. 

Time-resolved photoluminescence measurements are reported for InAsSbBi alloys grown by molecular beam epitaxy with Bi mole fractions ranging from 0 to 0.8%, yielding minority carrier lifetimes on the order of hundreds of nanoseconds. The minority carrier lifetimes extracted from the time-resolved photoluminescence measurements are comparable to those of lattice-matched InAsSb grown at the same respective temperatures. Nomarski imaging shows that smooth, droplet-free surface morphologies are obtained in 1 μm thick InAsSbBi epilayers grown at temperatures between 360 and 380 °C. The alloy composition-dependent bandgap energies for the InAsSbBi samples are determined from temperature-dependent steady-state photoluminescence measurements and compared with the tetragonal distortion measured by x-ray diffraction to determine the Sb and Bi mole fractions of each sample. The minority carrier lifetime and the achievable extension of the InAsSb(Bi) cut-off wavelength are analyzed as functions of alloy composition and compared with the performance of InAsSb layers with similar growth parameters.