Effects of lattice mismatch and bulk anisotropy on interband tunneling in broken-gap heterostructures

We have studied the effects of bulk anisotropy and the strain induced by lattice mismatch on the interband tunneling in broken-gap single-barrier InAsAlSbGaSb heterostructures and double-barrier InAsAlSbGaSbInAsAlSbGaSb heterostructures. We have used the eight-band k·p model and the scattering matrix method, combined with the Burt envelope function theory, to calculate the interband transmission coefficients through the broken-gap heterostructures. We have found a noticeable anisotropy of the transmission coefficients when the magnitude of the in-plane wave vector increases to around 0.25 nm-1. We have also found that the strain and the bulk anisotropy of quasiparticle dispersion produce additional peaks in the tunneling probability. For the double-barrier resonant-tunneling structures we discover a large spin splitting of the resonant-tunneling peaks caused by the lack of inversion symmetry. A strong influence of the strain induced by lattice mismatch appears in the current-voltage characteristics of the studied broken-gap heterostructures. In InAsAlSbGaSb structures the interband tunneling processes into the heavy-hole states contribute mainly to the peak current density if the sample is grown on InAs, but if the sample is grown on GaSb the interband tunneling processes into the light-hole states become the main contribution to the peak current density. As a result, the structure grown on GaSb has a much larger peak current density. This phenomenon was observed experimentally.