Be+ implanted GaInAsSb/GaSb photodiodes

Be+ implantation technology has been applied to realize p+/n− junctions in quaternary GaInAsSb n− alloys grown on GaSb substrates by liquid phase epitaxy. 2 μm cut-off mesa homojunctions have been prepared and characterized: the external quantum efficiency measured without any antireflecting coating reaches ηext = 0.5 at 1.8 μm. Room temperature dark reverse current densities Jrev (300K) = 1–5 mA cm−2 measured at V = −0.5 V are 10–100 times lower than those usually measured in GalnAsSb photodetectors; at low reverse polarization voltage the rapid decrease in the current levels as a function of the temperature leads to a strong increase in the performances of the photodiodes using simple Peltier cooling (Jrev (220 K) = 12 μA cm−2 at V = − 0.2 V). In the forward direction the behaviour of the dark currents as a function of the temperature leads us to conclude that diffusion is the dominant mechanism in these photodiodes in the range 320−220 K.