BE+ IMPLANTED GAINASSB GASB PHOTODIODES

Be+ implantation technology has been applied to realize p(+)/n(-) junc tions in quaternary GaInAsSb n(-) alloys grown on GaSb substrates by l iquid phase epitaxy. 2 mu m cut-off mesa homojunctions have been prepa red and characterized: the external quantum efficiency measured withou t any antireflecting coating reaches eta(ext) = 0.5 at 1.8 mu m. Room temperature dark reverse current densities J(rev) (300 K)= 1-5 mA cm(- 2) measured at V = -0.5 V are 10-100 limes lower than those usually me asured in GaInAsSb photodetectors; at low reverse polarization voltage the rapid decrease in the current levels as a function of the tempera ture leads to a strong increase in the performances of the photodiodes using simple Peltier cooling (J(rev) (220 K) = 12 mu A cm(-2) at V = -0.2 V). In the forward direction the behaviour of the dark currents a s a function of the temperature leads us to conclude that diffusion is the dominant mechanism in these photodiodes in the range 320-220 K.