High-performance Al/sub 0.15/Ga/sub 0.85/As/In/sub 0.53/Ga/sub 0.47/As MSM photodetectors grown by OMCVD

High-performance In/sub 0.53/Ga/sub 0.47/As metal-semiconductor-metal photodetectors using a thin lattice-mismatched Al/sub x/Ga/sub 1-x/As surface layer to enhance the Schottky-barrier height have been fabricated and characterized with 1.3- mu m laser sources. The dark leakage currents were reduced by a factor of five times with Al/sub 0.15/Ga/sub 0.85/As, when compared with GaAs or lattice-matched In/sub 0.52/Al/sub 0.48/As. The extrinsic quantum efficiency of a detector with a 1.0- mu m absorption region was measured to be 40%. Photocurrent measurement under various illumination powers showed a linear responsivity of 0.4 A/W, and no low-frequency gain was observed. Impulse measurements showed an FWHM (full width at half maximum) of about 60 ps with no appreciable diffusion tails.<
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