Large-area and visible response VPE InGaAs photodiodes

InGaAs photodiodes having diameters of 500 µm have been successfully fabricated by vapor-phase epitaxial techniques. Typical room-temperature performance characteristics at a bias voltage of -10 V are: quantum efficiency ≈80 percent (1 to 1.7 µm); dark current &ap120 nA; noise current &ap0.3 pA/Hz^1/2; capacitance &ap5 pF; and response time &ap3 ns. The useful spectral range of standard 100-µm-diameter diodes has been extended to short Wavelengths (about 0.5 µm) by a reduction in the thickness of the InP capping layer. Quantum efficiencies near 70 percent have been observed at 0.7 µm.