  We consider theoretically the electronic structure of quasi-two and
quasi-one-dimensional heterostructures comprised of III-V and II-VI
semiconductors such as InAs/GaInSb and HgCdTe. We show that not only a
Dirac-like dispersion exists in these materials when the energy gap approaches
zero, but that the states with opposite momentum are orthogonal (i.e. can be
described by a pseudo-spin), which suppresses backscattering and thereby
enhances the electron mobility, by analogy with the case of graphene. However,
unlike in graphene, a quasi-one-dimensional quantum wire with zero gap can be
realized, which should eliminate most of the scattering processes and lead to
long coherence lengths required for both conventional and ballistic electronic
devices.
