Enhancement of the intersubband Stark effect in strained InxGa1-xAs/InyAl1-yAs asymmetric coupled double quantum wells

Effect of an electric field on the electronic subbands in strained In0.65Ga 0.35As/In0.52Al0.48As coupled double quantum wells has been investigated th eoretically with the goal of producing the large Stark shifts and of their application possibilities to a tunable photodetector. The energy states, th e corresponding energy wavefunctions, the absorption peaks, and the Stark s hifts in strained In0.65Ga0.35As/In0.52Al0.48As coupled double quantum well s under applied electric fields are calculated by the transfer matrix metho d taking into account strain effects. The operation of this device is bared on the infrared absorption by the electrons in the ground state transited from the ground state subband to the excited state subbands of the coupled double quantum wells. When an electric field is applied to a coupled double quantum well, the shifts of the intersubband energy transitions and the ab sorption peaks in the coupled double quantum well are shifted much larger t han those in the single quantum well. The excited energy states with and wi thout applied electric fields in the In0.65Ga0.35As/In0.52Al0.48As coupled double quantum wells are strongly dependent on the In0.65Ga0.35As well widt h in comparison with their ground states. The coupling of the electronic su bband energies in the two In0.65Ga0.35As/In0.52Al0.48As quantum wells leads to an enhancement of the quantum-confined Stark effect. These results indi cate that strained In0.65Ga0.35As/In0.52Al0.48As coupled double quantum wel ls hold promise for potential applications to new kinds of optical modulati on devices and tunable photodetectors. (C) 2000 Elsevier Science B.V. All r ights reserved.