A. Gomyo et al., EFFECTS OF GAAS-SUBSTRATE SURFACE MISORIENTATION FROM (001) ON BAND-GAP ENERGY IN GA0.5IN0.5P, NEC research & development, 35(2), 1994, pp. 134-143
The dependence of band-gap energy (E(g)) on GaAs-substrate surface ori
entation was systematically studied for metalorganic vapor phase epita
xial growth Ga0.5In0.5P on GaAs at a growth temperature of 660-degrees
-C and a V/III ratio of 140 approximately 150. When the misorientation
angle theta(B) increased from the exact (001) to (111)B, E(g) decreas
ed from 1.85 eV and took a minimum value of 1.83 eV at theta(B) = 4-de
grees approximately 6-degrees. When theta(B) increased from 4-degrees
approximately 6-degrees to 15.8-degrees (i.e., (115)B), E(g) increased
steeply to a nearly-normal value of 1.90 eV. Then, E(g) gradually rea
ched a normal value of 1.918 eV, as theta(B) reached 54.7-degrees (i.e
., (111)B). The (115)B surface was found to be a critical misorientati
on. On the other hand, when increasing the misorientation angle theta(
A) from the exact (001) to (111)A by 4-degrees approximately 6-degrees
, E(g) increased sharply towards the normal value. For further increas
e of theta(A), E(g) still increased monotonically towards a value of 1
.916 eV at (111)A, which is virtually the same as that for the (111)B
surface. These E(g) behaviors were found to correspond to the degree o
f ordering characterized by the transmission electron microscopic stud
y of (111)B CuPt-type ordering on the Group III sublattice. A possible
explanation is given for the E(g) behaviors on the basis of step-terr
ace reconstructions on the grown surfaces.