Growth of order/disorder heterostructures in GaInP using a variation in V/III ratio

Abstract

CuPt ordering, resulting in formation of a natural monolayer {111} superlattice, occurs spontaneously during organometallic vapor phase epitaxial growth of Ga0.52In0.48P. The degree of order is found to be a function of the input partial pressure of the phosphorus precursor (PP) during growth. This is thought to be mainly due to the effect of PP on the surface reconstruction. A change in order parameter is associated with a change in the bandgap energy. Thus, a practical application of ordering is the production of a heterostructure by simply changing the flow rate of the P precursor during growth. Examination of transmission electron microscopy data and photoluminescence spectra indicates that order/disorder (O/D) (really less ordered on more ordered) and D/O heterostructures formed by growth using PH3 at a temperature of 620°C are graded over several thousands of A: The ordered structure from the lower layer persists into the upper layer. Similar results were obtained at 620°C when the first layer was grown using PH3 (V/III=160) and the second using tertiarybutylphosphine (TBP) (V/III=5). The use of a temperature of 670°C to produce heterostructures using either PH3 or TBP yields a totally different behavior. Abrupt D/O and O/D heterostructures can be produced by changing PP during the growth cycle. The cause of this difference in behavior is not entirely clear. However, it appears to be related to a very slow change in the surface reconstruction, measured using surface photo absorption, when the PH3 partial pressure is changed at 620°C.