Three-color (λp1∼3.8 μm, λp2∼8.5 μm, and λp3∼23.2 μm) InAs/InGaAs quantum-dots-in-a-well detector

We report a three-color InAs/InGaAs quantum-dots-in-a-well detector with center wavelengths at similar to3.8, similar to8.5, and similar to23.2 mum. We believe that the shorter wavelength responses (3.8 and 8.5 mum) are due to bound-to-continuum and bound-to-bound transitions between the states in the dot and states in the well, whereas the longer wavelength response (23.2 mum) is due to intersubband transition between dot levels. A bias-dependent activation energy similar to100 meV was extracted from the Arrhenius plots of the dark currents, which is a factor of 3 larger than that observed in quantum-well infrared photodetectors operating at comparable wavelengths. (C) 2003 American Institute of Physics.