INSITU CONTROL OF HETEROINTERFACE QUALITY IN MOVPE BY SURFACE PHOTOABSORPTION

Exchange reaction of Group V atoms is in situ monitored on a submonolayer scale during the MOVPE growth of pseudomorphic InAs/InP heterostructures on (001) InP substrate by the surface photo-absorption (SPA) method. When arsine was supplied onto the In surface of InP above 360-degrees-C, the substitution between As atoms of impinging AsH3 molecules and P atoms of InP surface was detected as a change in surface reflectivity. The reaction proceeded to about 0.4 monolayer exchange at 400-degrees-C, and was suppressed to less than 0.1 monolayer at 350-degrees-C. In contrast, the exchange between P atoms of impinging PH3 and As atoms of InAs surface was less than 0.1 monolayer below 400-degrees-C. To verify the formation of a metallurgically abrupt heterointerface, InAs/InP single quantum wells with 1-5 monolayers were grown at 350-degrees-C, and were characterized by transmission electron microscopy and photoluminescence. Atomic layer epitaxy was used to control precisely the InAs well thickness with an accuracy of one monolayer. A sharp and an intense quantum well photoluminescence was observed with a reasonable shift of emission energy due to the quantum size effect up to five InAs monolayers, indicating that metallurgically abrupt and atomically flat heterointerfaces were fabricated as designed.