Large-area and visible response VPE InGaAs photodiodes

InGaAs photodiode having diameters of 500 microns have been successfully fabricated by vapor-phase epitaxial techniques. Typical room-temperature performance characteristics at a bias voltage of -10 V are: quantum efficiency of approximately 80 percent (1 to 7 microns); dark current of approximately 120 nA; noise current of approximately 0.3 pA/Hz exp 1/2; capacitance of approximately 5 pF; and response time of approximately 3 ns. The useful spectral range of standard 100-micron-diameter diodes has been extended to short wavelenghts (about 0.5 micron) by a reduction in the thickness of the InP capping layer. Quantum efficiencies near 70 percent have been observed at 0.7 micron.