THE ENHANCED STARK EFFECTS OF COUPLED QUANTUM-WELLS AND THEIR APPLICATION TO TUNABLE IR PHOTODETECTORS

A tunable asymmetric coupled quantum well far-infrared photodetector i s proposed in this paper. The basic asymmetric coupled quantum wells a re composed of two quantum wells separated by a thin barrier. In this way, the electron in each well interacts strongly with other electrons to achieve a large Stark tuning effect. The eigenenergies and the wav e functions of the quantum-well structures are solved by the self-cons istent method, and the effect of the exchange interaction on the groun d-state subband has also been taken into account. The absorption coeff icient is evaluated by the density-of-states formalism. Based on theor etical calculations, tuning ranges from 8.2 to 11.3 mum and 7.8 to 10. 5 mum are predicted for the proposed asymmetric coupled-quantum-well s tructure and high-low coupled-quantum-well structure, respectively. Th is tuning capability is achieved by varying the applied electric field in the 20-90-kV/cm range.