Detectors operating at 2 μm are important for several applications including optical communication and atmospheric remote sensing. In this letter, fabrication of 2 μm photodetectors using an InGaSb substrate is reported. The ternary substrates were grown using vertical Bridgmann technique and Zn diffusion was used to fabricate p–n junction diodes and photodiodes. Dark current measurement reveals that the breakdown voltage is in the 0.75 to 1 V range. Spectral response measurements indicated a 2 μm responsivity of 0.56 A/W corresponding to 35% quantum efficiency. Photodiode performance was compared to similar devices fabricated on binary substrates.