High-responsivity GaInAs/InP quantum well infrared photodetectors grown by low-pressure metalorganic chemical vapor deposition

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Abstract
We have studied the dependence of the well doping density in n-type GaInAs/InP quantum well IR photodetectors (QWIPs) grown by low-pressure metalorganic chemical vapor deposition. Three identical GaInAs/InP QWIP structures were grown with well sheet carrier densities of 1 by 1011 cm-2, 3 by 1011 cm-2, and 10 by 1011 cm-2; all three samples had very sharp spectral response at (lambda) equals 9.0 micrometers . We find that there is a large sensitivity of responsivity, dark current, noise current, and detectivity with the well doping density. Measurements revealed that the lowest-doped samples had an extremely low responsivity relative to the doping concentration while the highest-doped sample had an excessively high dark current relative to doping. The middle-doped sample yielded the optimal results. This QWIP had a responsivity of 33.2 A/W and operated with a detectivity of 3.5 by 1010 cmHz1/2W-1 at a bias of 0.75 V and temperature of 80 K. This responsivity is the highest value reported for any QWIP in the (lambda) equals 8-9 micrometers range. Analysis is also presented explaining the dependence of the measured QWIP parameters to well doping density.

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