CONDUCTION INTERSUBBAND (IN,GA)AS GAAS QUANTUM-DOT INFRARED PHOTODETECTORS/

The authors report a 40-period (In,Ga)As/GaAs normal-incidence quantum dot infrared photodetector operating in the wavelength range 8-14 mu m. A primary intersubband transition peak is observed at a wavelength of 12.5 mu m (E-0 --> E-1), and a secondary peak at 11.3 mu m (E-0 --> E-2). The measured intersubband energy spacing is in good agreement w ith calculations. The normal-incidence peak responsivity at the bias v oltage of -6V is similar to 0.17 A/W. The background-limited performan ce temperature of our devices is found to be 62K.