A paper describes a computational study of effects of doping in a quantum well (QW) comprising a 10-nm-thick layer of InAs sandwiched between two 21-nm-thick AlSb layers.

Heretofore, InAs/AlSb QWs have not been useful as interband gain devices because they have type-II energy-band-edge alignment, which causes spatial separation of electrons and holes, thereby leading to weak interband dipole matrix elements. In the doping schemes studied, an interior sublayer of each AlSb layer was doped at various total areal densities up to 5 × 1012 cm-2. It was found that (1) proper doping converts the InAs layer from a barrier to a well for holes, thereby converting the heterostructure from type II to type I; (2) the resultant dipole matrix elements and interband gains are comparable to those of typical type-I heterostructures; and (3) dipole moments and optical gain increase with the doping level. Optical gains in the transverse magnetic mode can be almost ten times those of other semiconductor material systems in devices used to generate medium-wavelength infrared (MWIR) radiation. Hence, doped InAs/AlSb QWs could be the basis of an alternative material system for devices to generate MWIR radiation.

This work was done by K. I. Kolokolov and C. Z. Ning of Ames Research Center. For further information, access the Technical Support Package (TSP) free on-line at www.techbriefs.com/tsp under the Physical Sciences category.

Inquiries concerning rights for the commercial use of this invention should be addressed to

the Patent Counsel, Ames Research Center, (650) 604-5104.

Refer to ARC-15157-1

NASA Tech Briefs Magazine

This article first appeared in the January, 2005 issue of NASA Tech Briefs Magazine.

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