ABSTRACTWe demonstrate long wavelength quantum well infrared photodetectors (QWIP) with GaAs quantum wells and GalnP barriers grown using gas-source molecular beam epitaxy. Wafers were grown with varying well widths. The optimum well width was 75 Å, which resulted in a detection peak at 13 μm and a cutoff wavelength of 15 μm Dark current measurements of the samples with 15 μm cutoff wavelength show low dark current densities. Preliminary focal plane array imaging is demonstrated.