GaAs(1-y-z)P(y)Bi(z) - New Near Lattice-Matched Materials to GaAs

The
IRG has developed a new material, GaAs_1-y-zP_yBi_z,
as an
alternative to the nitride–based
bismide
materials,
specifically GaAs_1-y-zBi_yN_z.
Alloying in both Bi and N
complicates growth, since
both elements
are sparingly
soluble
in GaAs.
GaAs_1-yP_y,
on the other hand, shows complete solid solubility over all y.
Consequently
 GaAs_1-yP_y
acts as the host material
for Bi incorporation
in the new material. These alloys are predicted, initially using DFT
calculations, to have a tunable band
gap in the desirable ~1 eV range
and, simultaneously, GaAs_1-y-zP_yBi_z
is
lattice matched to GaAs
at y~10z.
We
have synthesized,
using metal organic vapor phase epitaxy, GaAs_1-y-zP_yBi_z
alloys.
Our
collaborators at the University of Bari (Italy) have used ellipsometry to
determine band gaps reported in the table to the right. Furthermore, we have
achieved the highest Bi
content at lattice
match to GaAs
to date. We
are exploring the electronic structure of these new materials as well as the
optical properties.