Systematic study of different transitions in high operating temperature quantum dots in a well photodetectors

We report a systematic study of different transitions in quantum dots-in-a-well infrared photodetectors in order to optimize the signal to noise ratio of the detector. Bound to continuum transitions offer very high extraction probability for photoexcited electrons but poor absorption coefficient, while the bound to bound transitions have higher absorption but poorer extraction probability. Bound to quasibound transitions are optimum for intermediate values of electric fields with superior signal to noise ratio. The bound to quasibound device has the detectivity of 4 × 10 11 cm Hz 1 / 2 W − 1 (3V, f / 2 system) at 77 K and 7.4 × 10 8 cm Hz 1 / 2 W − 1 at 200 K, which is highest reported detectivity at 200 K for detector with long wave cutoff wavelength.