Highly mismatched semiconductor alloys such as GaNAs and GaBiAs have several
novel electronic properties, including a rapid reduction in energy gap with
increasing x and also, for GaBiAs, a strong increase in spin orbit- splitting
energy with increasing Bi composition. We review here the electronic structure
of such alloys and their consequences for ideal lasers. We then describe the
substantial progress made in the demonstration of actual GaInNAs telecomm
lasers. These have characteristics comparable to conventional InP-based
devices. This includes a strong Auger contribution to the threshold current. We
show, however, that the large spin-orbit-splitting energy in GaBiAs and GaBiNAs
could lead to the suppression of the dominant Auger recombination loss
mechanism, finally opening the route to efficient temperature-stable telecomm
and longer wavelength lasers with significantly reduced power consumption.Comment: 27 pages, 11 figure
