We conducted an experimental study of back-side-illuminated InGaAs photodiodes grown on GaAs and sensitive in the short-wave infrared up to 2.4 mum. Standard metamorphic InGaAs or IR-transparent InAlAs buffers were grown by molecular-beam epitaxy. We studied dark current and photocurrent as a function of buffer thickness, buffer material, and temperature. A saturation of the dark current with buffer thickness was not observed. The maximum resistance area product was similar to10 Omega cm(2) at 295 K. The dark current above 200 K was dominated by generation-recombination current. A pronounced dependence of the photocurrent on the buffer thickness was observed. The peak external quantum efficiency was 46% (at 1.6 mum) without antireflective coating. (C) 2003 American Institute of Physics.