The authors report a two-color, colocated quantum dot based imaging system used to take multicolor images using a single focal plane array (FPA). The dots-in-a-well (DWELL) detectors consist of an active region composed of InAs quantum dots embedded in In.15Ga.85As quantum wells. DWELL samples were grown using molecular beam epitaxy and fabricated into 320×256 focal plane arrays with indium bumps. The FPA was then hybridized to an Indigo ISC9705 readout circuit and tested. Calibrated blackbody measurements at a device temperature of 77K yield midwave infrared and long wave infrared noise equivalent difference in temperature of ∼55 and 70mK.

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Radio–frequency magnetron sputter epitaxy was employed for the synthesis of n–type modulation doped Si/Si1−xGex heterostructures. Si channels were grown coherently on sputtered, compositionally graded Si1−xGex buffers of low defect density, and remotely doped with phosphorus by plasma assisted gas phase doping. Magnetotransport measurements on these films revealed Shubnikov–de Haas oscillations in the longitudinal and the integer quantum Hall effect in the transverse magnetoresistance, demonstrating the presence of a two–dimensional electron gas. At T=1.6 K and sheet densities of 1012 cm−2, electron mobilities as high as 15 800 cm2/V s give evidence of the excellent structural and electronic properties achievable by the sputter growth technique.

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