Intraband absorption for normal illumination in quantum dot intermedíate band solar cells

n the current intermedíate band solar cells made with InAs quantum dots (QDs) in GaAs, the ransitions by absorption of photons between the intermedíate band and the conduction band for llumination normal to the cell surface is very weak or, more often, undetectable. We model the QD as a jarallelepiped potential well and calcúlate the envelope function of the electrón wavefunctions. By jbtaining the dipolar matrix elements we find that, with the present shapes, this absorption is ,'orbidden or very weak. Deeper QDs with smaller base dimensions should be made to permit this