| Popis: |
Intermixing effect in type-II Ga 0.6 In 0.4 Sb/InAs superlattices is studied. The interdiffusion of both group- III and group V atoms across the heterointerface modifies the superlattices optical properties and electronic structures. The intermixed-induced strain has different effects on the band structure of the respective strained layers. Conduction band is undergone successive changes where the barrier height was initially increased in potential and subsequently became lower than the as-grown one for increasing extent of intermixing. Consequently the confinement profile is tuned from an abrupt interface to a graded shape. Intersubband transition is investigated in the intermixed superlattices where the absorption peak wavelength is red shifted continuously from the as grown 11.7 to the interdiffused 12.5 micrometers . Both the intermixed absorption and responsivity are reducing in magnitude. However, dark current is reduced at initial stage of intermixing as a result of the increase in confinement potential and the effective barrier width. Detectivity at 77 K is enhanced for the intermixed detector from 2.5 X 10 11 to 3 X 10 11 cm(root)Hz/W, which is comparable to the MCT detector. |
