We present an approach to realize antimonide based superlattices on silicon substrates without using conventional
Indium-bump hybridization. In this approach, PIN based superlattice detectors are grown on top of a 60 nm Al0.6Ga0.4Sb
sacrificial layer on a GaSb host substrate. Following the growth, the individual pixels are transferred using our epitaxiallift
off technique, which consists of a wet-etch to undercut the pixels followed by a dry-stamp process to transfer the
pixels to a silicon substrate prepared with a gold layer. Structural and optical characterization of the transferred pixels
was done using an optical microscope, scanning electron microscopy and photoluminescence. The interface between the
transferred pixels and the new substrate was abrupt and no significant degradation in the optical quality was observed.
An Indium-bump-free membrane detector was then fabricated using this approach. Spectral response measurements
provided a 100% cut-off wavelength of 4.3 μm at 77 K. The performance of the membrane detector was compared to a
control detector on the as-grown substrate. The membrane detector was limited by surface leakage current. The proposed
approach could pave the way for wafer-level integration of photonic detectors on silicon substrates, which could
dramatically reduce the cost of these detectors.
Detectivity of mid-wave infrared (MWIR) detectors based on InAs/GaSb type II strained layer superlattices (T2SLs) can be significantly enhanced at select wavelengths by integrating the detector with a back-side illuminated plasmonic coupler. The application of a simple metal-T2SL structure directly on the GaSb substrate can result in radiation losses into the substrate due to the low refractive index of T2SL layer. However, insertion of a higher refractive index material, such as germanium (Ge), into the metal-SLS structure can confine the surface plasmon waveguide (SPW) modes to the surface. In this work, metal (Au)-Ge-T2SL structures are designed with an approximately 100 nm thick Ge layer. The T2SL layer utilized a p-i-n detector design with 8 monolayers (MLs) InAs/8 MLs GaSb. A plasmonic coupler was then realized inside the 300 μm circular apertures of these single element detectors by the formation of a corrugated metal (Au) surface. The T2SL single element detector integrated with an optimized plasmonic coupler design increased the quantum efficiency (QE) by a factor of three at an operating temperature of 77 K and 3 to 5 μm illumination wavelength, compared to a reference detector structure, and each structure exhibited the same level of dark current.
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