We have demonstrated a dual-band quantum well infrared photodetector (QWIP) exhibiting simultaneous
photoresponse both in the mid and the long wavelength atmospheric windows of 3-5 μm and of 8-12 μm, but the
device only has two ohmic contacts. The structure of the device was achieved by sequentially growing a mid
wavelength part (MWQWIP) followed by a long wavelength part (LWQWIP) separated by an n+ layer. Comparing
with the conventional dual-band QWIP device utilizing three ohmic contacts, our QWIP is promising to greatly
facilitate the two-color focal plane array (FPA) fabrication by reducing the number of the indium bump per pixel
from three to one just like a monochromatic FPA fabrication; another advantage may be that this QWIP FAP boasts
two-color detection capability while only using a monochromatic readout integrated circuit.