Wafer-fused mid-infrared optical up-converter based on MOCVD grown InSb

InSb has been intensively studied in decades and widely used for fabricating high-performance devices because of its good chemical stability, low effective mass, high electron and hole mobility, and narrow band gap. The most important device applications for InSb are in thermal image sensing in the mid-infrared (3-5 μm) spectral range. The industry standard for fabricating InSb-based focal plane arrays for thermal imaging is based on indium bump technology to interconnect the InSb array to a Si-based readout integrated circuit chip. This hybridization is a "one-piece-at-a-time" process and thus time-consuming and costly. An alternative approach is to employ a device that up-converts mid-infrared light to a wavelength below 1 μm, which can then efficiently be detected by Si charged coupled devices. We reported herein such a mid-infrared optical up-converter based on InSb using wafer fusion technology. The up-conversion device consists of an InSb p⁺nn ⁺ photodiode and a GaAs/AlGaAs LED, which were grown separately and wafer-bonded together. Experimental results demonstrated mid-infrared to 0.84 μm up-conversion operation at 77K. The measured LED external efficiency and photodiode responsivity show that an external up-conversion efficiency of 0.093 W/W was obtained. Effects of electrical gain and photon recycling inside this integrated device are discussed.