InGaAs/InAlAs quantum well infrared photodetectors for operation in the 1.7 to 3.1 µm wavelength range

InGaAs/InAlAs superlattice structures with a wider central quantum well have been developed for quantum well infrared photodetectors (QWIPs) for operation between 1.7 and 3.1 microns, a range normally unreachable with conventional intraband transitions in this type of material. With this approach the limitation of having bound states only with energies below the barrier no longer holds, therefore it becomes possible to detect energies higher than the upper limit imposed by the bandoffset of the materials. In this work theoretical as well as experimental results on the absorption of such QWIP, which are in excellent agreement, are presented showing photocurrent around 2.6 microns.