Room Temperature 3.5-<inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math> </inline-formula> Mid-Infrared InAs Photovoltaic Detector on a Si Substrate

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We report a mid-infrared InAs p-i-n photovoltaic detector on a Si substrate operating at room temperature with a cutoff wavelength at 3.5 $\mu \text{m}$ . The large 11.6% lattice mismatch between the device layer (InAs) and the Si substrate is accommodated by employing a compositionally graded buffer layer technique using solid-source molecular beam epitaxy and a commercially available GeSi substrate. An Al x In1– x As graded buffer layer is used to linearly scale the lattice constant from AlAs to InAs with an increasing $x$ value. The photovoltaic detector has a responsivity of 0.57 A/W, measured using a blackbody source maintained at 700 °C.