Hole diffusivity in GaAsBi alloys measured by a picosecond transient grating technique

• Published in: Applied physics letters Vol. 98; no. 8; pp. 082115 - 082115-3
• Main Authors: Nargelas, S., Jarašiūnas, K., Bertulis, K., Pačebutas, V.
• Format: Journal Article
• Language: English
• Published: American Institute of Physics 21-02-2011
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.3557047

We applied a time-resolved transient grating technique for investigation of nonequilibrium carrier dynamics in
GaAs
1
−
x
Bi
x
alloys with
x
=
0.025
-
0.063
. The observed decrease in carrier bipolar diffusivity with lowering temperature and its saturation below 80 K revealed a strong localization of nonequilibrium holes. Thermal activation energy
Δ
E
a
=
46

meV
of diffusivity and low hole mobility value
μ
h
=
10
-
20

cm
2
/
V
s
at room temperature confirmed the hybridization model of the localized Bi states with the valence band of GaAs. Nonlinear increase in carrier recombination rate with the Bi content,
1
/
τ
R
∝
Bi
(
x
)
3.2
indicated an increasing structural disorder in the alloy.