A three wavelength infrared focal plane array detector element

We have demonstrated a novel three wavelength InGaAs focal plane array pixel element for detection at wavelengths from 0.9-2.6 μm, where each of three wavelength sensitive detectors are individually addressable. This device consists of successively smaller bandgap layers of In/sub x/Ga
₁
spl minus/x/As (x/spl ges/0.53), separated by compositionally graded layers of InAs/sub y/P
₁
spl minus/y/ to decrease defects induced by lattice mismatch strain with the InP substrate. The various layers were selectively removed so that p-n junctions with different wavelength response are formed. The three detectors have quantum efficiencies between 55 and 95% for front illumination and 15 and 60% for back illumination, and dark currents from 0.01 to 10 mA/cm
²
.