Speaker
Dr
J.C. Bourgoin
(Université Pierre et Marie Curie)
Description
Self-supported thick (larger than 200 microns), non intentionally doped, epitaxial
GaAs layers are good candidates for X-ray imaging for the following reasons. Their
electronic properties are homogeneous over large areas (4 inches diameter), they
can be grown at low cost, the technology to realize pixel detectors of any size is
standard, the defect concentration is very low and the fluorescence yield is low.
The low defect concentration permits a large minority carrier lifetime, which is at
least 100 times larger than in bulk grown materials. Here we demonstrate that the
mobility-lifetime product is high. Using Deep Level Transient Spectroscopy combined
with photon counting, we evaluate the electron and hole lifetimes to be at least 10-
6 s, leading to electrons and holes mobility-lifetime products of 8×10-3 cm2V-1
and 4×10-4 cm2V-1, which are 100 times higher than the standard values (taken from
bulk materials) attributed to GaAs, i.e. 8×10-5 cm2V-1 for electrons and 4×10-6
cm2V-1 for holes; about 2 times larger than for the best CdTe materials, i.e. 3×10-
3 cm2V-1 for electrons and 2×10-4 cm2V-1 for holes.
Primary author
Guoaci Sun
(Université Pierre et Marie Curie)
Co-author
Dr
J.C. Bourgoin
(Université Pierre et Marie Curie)
