Highdetectivity AlInSb Midinfrared Photodiode Sensors with Dislocation Filter Layers for Gas Sensing

A midinfrared photodiode is developed for methane gas sensing based on the highly mismatched AlInSb/GaAs system. Inserting optimized dislocation filter layers (DFLs) in the buffer layer reduced the threading dislocation density in the active layer to less than one‐third of that in the photodiode without DFLs. This improvement produces a high normal incidence detectivity of 1.8 × 10 9 cm √Hz W −1 at 3.3 μm, which is more than twice the highest detectivity previously obtained for a photodiode without DFLs.