We analyze the optical and transport consequences of the existence of ordered and random domains in partially ordered samples of alloys. Using atomistic empirical pseudopotential simulations, we find that the band alignment between random and ordered domains changes from type I to type II at This leads to an increase by two to three orders of magnitude in the radiative lifetime of the electron–hole recombination. This can explain the experimentally observed mobility-lifetime product behaviors with changing Al concentration. The type I to type II transition results from a competition between the ordering-induced band folding effect and hole confinement on Ga-rich monolayers within the ordered structure.
REFERENCES
1.
D.
Korakakis
, K. F.
Ludwig
, Jr., and T. D.
Moustakas
, Appl. Phys. Lett.
71
, 72
(1997
);E.
Iliopoulos
, K. F.
Ludwig
, Jr., T. D.
Moustakas
, and S. N. G.
Chu
, Appl. Phys. Lett.
78
, 463
(2001
).2.
L.
Kirste
, D. G.
Ebling
, Ch.
Haug
, R.
Brenn
, K. W.
Benz
, and K.
Tillmann
, Mater. Sci. Eng., B
82
, 9
(2001
);D. G.
Ebling
, L.
Kirste
, K. W.
Benz
, N.
Teofilov
, K.
Thonke
, and R.
Sauer
, J. Cryst. Growth
227-228
, 453
(2001
).3.
D.
Doppalapudi
, S. N.
Basu
, K. F.
Ludwig
, Jr., and T. D.
Moustakas
, J. Appl. Phys.
84
, 1389
(1998
);D.
Doppalapudi
, S. N.
Basu
, and T. D.
Moustakas
, J. Appl. Phys.
85
, 883
(1999
).4.
P.
Ruterana
, G.
Nouet
, W.
Van der Stricht
, I.
Moerman
, and L.
Considine
, Appl. Phys. Lett.
72
, 1742
(1998
);P.
Ruterana
, G.
De Saint Jores
, M.
Laügt
, F.
Omnes
, and E.
Bellet-Amalric
, Appl. Phys. Lett.
78
, 344
(2001
);P.
Ruterana
, G.
De Saint Jores
, and F.
Omnes
, Mater. Sci. Eng., B
82
, 203
(2001
);M.
Laüght
, E.
Bellet-Amalric
, P.
Ruterana
, and F.
Omnes
, Phys. Status Solidi B
236
, 729
(2003
).5.
M. K.
Behbehani
, E. L.
Piner
, S. X.
Liu
, N. A.
El-Masry
, and S. M.
Bedair
, Appl. Phys. Lett.
75
, 2202
(1999
).6.
M.
Misra
, D.
Korakakis
, H. M.
Ng
, and T. D.
Moustakas
, Appl. Phys. Lett.
74
, 2203
(1999
).7.
8.
In our simulations, we assume that random/ordered interfaces are oriented along the crystal planes. The reasons are twofold: First, a cross-sectional transmission electron microscopy (TEM) micrograph of ordered domain structure in Ref. 3 shows sharper and larger area random/ordered interface planes perpendicular to the (0001) substrate plane, consistent with our choice. Second, we wish to focus here on the difference in the bulk properties of the ordered and random domains, rather than on specific interface atomic structure. Each plane contains equal numbers of the Al-preferred and Ga-preferred cation sites of the ordered alloy. This allows us to avoid extra complications of considering different terminations (Ga-rich and Al-rich) of the ordered phase in contact with the random phase.
9.
K.
Kim
, P. R. C.
Kent
, A.
Zunger
, and C. B.
Geller
, Phys. Rev. B
66
, 045208
(2002
).10.
11.
12.
13.
14.
15.
I.
Vurgaftman
, J. R.
Meyer
, and L. R.
Ram-Mohan
, J. Appl. Phys.
89
, 5815
(2001
).16.
17.
A.
Rubio
, J. L.
Corkill
, M. L.
Cohen
, E. L.
Shirley
, and S. G.
Louie
, Phys. Rev. B
48
, 11
810
(1993
).18.
W.
Shan
, J. W.
Ager
III, W.
Walukiewicz
, E. E.
Haller
, B. D.
Little
, J. J.
Song
, M.
Schurman
, Z. C.
Feng
, R. A.
Stall
, and B.
Goldenberg
, Appl. Phys. Lett.
72
, 2274
(1999
).19.
20.
In a realistic alloy, the shape of the ordered domains is more complex than in our model systems, and the realistic ordered/random interfaces may not be atomically sharp. That may explain why the observed change (Ref. 6) of the μτ product with is more gradual than the drop of the transition amplitude in Fig. 1(c).
This content is only available via PDF.
© 2004 American Institute of Physics.
2004
American Institute of Physics
You do not currently have access to this content.
