10–16 μm Broadband quantum well infrared photodetector

A very long wavelength broadband infrared detector, sensitive over a 10–16 μm spectral range, based on ${\mathrm{GaAs/Al}}_x{\mathrm{Ga}}_{\text{1−x}}\mathrm{As}$ quantum wells grown by molecular beam epitaxy, has been demonstrated. Wavelength broadening of ${\mathrm{\Delta \lambda /\lambda }}_p\text{∼42\%}$ is observed to be about a 400% increase compared to a typical bound-to-quasibound quantum well infrared photodetector (QWIP). In this device structure, which is different from typical QWIP device structures, two different gain mechanisms associated with photocurrent electrons and dark current electrons were observed and explained. Even with broader response, $D^{*}{\text{∼1×10}}^{10}\hspace{0.17em}\mathrm{cm}\sqrt{\mathrm{Hz}}/\mathrm{W}$ at $\text{T=55\hspace{0.17em}}\mathrm{K}$ is comparable to regular QWIPs with similar cutoff wavelengths.