Feasibility study of CdF/sub 2//CaF/sub 2/ intersubband transition lasers

Theoretical analysis of CdF/sub 2/-CaF/sub 2/ heterostructure intersubband transition lasers on Si substrates was carried out and their threshold current density was estimated. We found that these lasers make 1.35 /spl mu/m operation feasible due to their large conduction band discontinuity at the CdF/sub 2/-CaF/sub 2/ heterointerfaces and the large optical confinement factor they exhibit when Si optical confinement layers are used. With active quantum wells of 10 periods their threshold current density is 350 A/cm/sup 2/ even at room temperature.