II-VI semiconductors are less well developed than III-Vs but offer some tantalizing advantages:
The results can be spectacular. For instance, excitons can have 40 meV binding energies leading to stable excitons even at room temperature and enhanced strong exciton-photon coupling in a microcavity.
The best chance of observing clear Bose-Einstein condensation in the solid-state is with polaritons in semiconductor microcavities. A polariton is the hybridized mode of an exciton-photon pair. GaAs quantum wells are not ideal for this as the excitons are weakly bound such that an electron-hole plasma forms at relatively modest densities. A ZnSe quantum well is more promising as the Coulomb interactions are enhanced. The traditional problem is the difficulty in growing a semiconductor mirror in a ZnSe based system. This problem has been bypassed. A new fabrication technology, based on an epitaxial liftoff technique using a novel MgS sacrificial layer [Balocchi et al. (2005)], has been realised, perfected and successfully applied to the fabrication of hybrid ZnSe based microcavities that operate in both the weak and strong coupling regimes [Curran et al. (2007)]. A thin MgS layer allows for the liftoff of the active layers which can then be deposited onto a dielectric mirror. Strong coupling has been demonstaretd using this approach [Curran et al. (2007)]. But will they condense...
© Arran Curran. Last modification: 29-Oct-2008