M. Ilg et al., INVESTIGATION OF INAS SUBMONOLAYER AND MONOLAYER STRUCTURES ON GAAS(100) AND (311) SUBSTRATES, Journal of applied physics, 74(12), 1993, pp. 7188-7197
We demonstrate a new route to the synthesis of InAs monolayer structur
es in GaAs by bridging the fundamental gap between the requirement of
the lowest possible substrate temperatures to suppress In segregation
and the necessity to maintain sufficiently high temperatures for the g
rowth of low-defect density material. This mediation between opposing
aspects of the molecular beam epitaxy of these InAs structures is achi
eved by a modulation of the substrate temperature and by a minimizatio
n of the amount of GaAs cap material grown at low temperature. High-re
solution x-ray diffraction and high-resolution electron microscopy com
bined with photoluminescence (PL) and PL excitation spectroscopies rev
eal excellent structural properties for our series of (311) and (100)
oriented submonolayer and monolayer structures. A comparison of our PL
results with already published data proves our In concentration profi
les to be very sharp and from a numerical analysis we deduce an upper
limit of 0.2 for the In segregation probability in these structures. I
n addition we obtain as upper limits for the conduction band offsets Q
(c)(100) less-than-or-equal-to 0.4 and Q(c)(311) less-than-or-equal-to
0.55 for (100) and (311) orientations, respectively.