Images of the steady-state luminescence of passivated GaAs self-standing films under excitation by a tightly focussed laser are analyzed as a function of light excitation power. While unipolar diffusion of photoelectrons is dominant at very low light excitation power, an increased power results in a decrease of the diffusion constant near the center of the image due to the onset of ambipolar diffusion. The results are in agreement with a numerical solution of the diffusion equations and with a physical analysis of the luminescence intensity at the centre of the image, which permits the determination of the ambipolar diffusion constant as a function of electron concentration.

1.
R. A.
Smith
,
Semiconductors
(
Cambridge University Press
,
Cambridge, England
,
1978
).
3.
J.
Young
and
H.
Van Driel
,
Phys. Rev. B
26
,
2147
(
1982
).
4.
H. A.
Zarem
,
P. C.
Sercel
,
J. A.
Lebens
,
L. E.
Eng
,
A.
Yariv
, and
K. J.
Vahala
,
Appl. Phys. Lett.
55
,
1647
(
1989
).
5.
K.
Gulden
,
H.
Lin
,
P.
Kiesel
,
P.
Riel
,
G.
Döhler
, and
K.
Ebeling
,
Phys. Rev. Lett.
66
,
373
(
1991
).
6.
B.
Ruzicka
,
L.
Werake
,
H.
Samassekou
, and
H.
Zhao
,
Appl. Phys. Lett.
97
,
262119
(
2010
).
7.
H.
Zhao
,
M.
Mower
, and
G.
Vignale
,
Phys. Rev. B
79
,
115321
(
2009
).
8.
H.
Zhao
,
Appl. Phys. Lett.
92
,
112104
(
2008
).
9.
L.
Chao
,
G.
Cargill
,
E.
Snoeks
,
T.
Marshall
,
J.
Petruzzello
, and
M.
Pashley
,
Appl. Phys. Lett.
74
,
741
(
1999
).
10.
I.
Favorskiy
,
D.
Vu
,
E.
Peytavit
,
S.
Arscott
,
D.
Paget
, and
A. C. H.
Rowe
,
Rev. Sci. Instrum.
81
,
103902
(
2010
).
11.
J.
Lowney
and
H.
Bennett
,
J. Appl. Phys.
69
,
7102
(
1991
).
12.
S.
Arscott
,
E.
Peytavit
,
D.
Vu
,
A. C. H.
Rowe
, and
D.
Paget
,
J. Micromech. Microeng.
20
,
025023
(
2010
).
13.
R.
Nelson
and
R.
Sobers
,
J. Appl. Phys.
49
,
6103
(
1978
).
14.
R.
Brenot
,
R.
Vanderhaghen
,
B.
Drévillon
,
P.
Roca i Cabarrocas
,
R.
Rogel
, and
T.
Mohammed-Brahim
,
Thin Solid Films
383
,
53
(
2001
).
15.
P.
Asbeck
,
J. Appl. Phys.
48
,
820
(
1977
).
16.
T.
Kuriyama
,
T.
Kamiya
, and
H.
Yanai
,
Jpn. J. Appl. Phys., Part 1
16
,
465
(
1977
).
You do not currently have access to this content.