InAs0.7Sb0.3 Bulk Photodiodes Operating at Thermoelectric‐Cooler Temperatures

Current–voltage and photoelectrical characteristics of InAs0.7Sb0.3 photodiodes grown onto InAs substrates are investigated in the interval of 212–330 K, i.e., the “thermoelectrical temperature range”. The impacts of mesa diameter, buffer layer thickness, and cooling on the zero‐bias resistance and spectral responsivity are described and analyzed. At low temperatures, the dynamic zero‐bias resistance dominat the serial one, resulting in the specific detectivity at 6.5 µm and at T = 233 K being as high as 3.2 · 108 cm Hz1/2 W−1 for a flat‐plate photodiode. Low energy gap flip‐chip photodiodes with InAsSb0.3 absorbing layer are fabricated. These photodiodes exhibit reasonably high values of specific detectivity and responsivity at 6.5 μm when cooled down to 233 K which is essential for many spectroscopic measurements including pyrometry and gas analysis.