SI INTRALAYERS AT GAAS ALAS AND GAAS/GAAS JUNCTIONS - POLAR VERSUS NONPOLAR INTERFACES/

The effect of inserting thin Si intralayers at GaAs/AlAs and GaAs/GaAs interfaces has been studied by photoelectron spectroscopy (PES) using synchrotron radiation. Results from polar and nonpolar interfaces are compared by analyzing samples grown by molecular-beam epitaxy on (100 ) and (110) substrates, respectively. The Si intralayers were inserted by an improved delta-doping method in a concentration of 2.2X10(14) c m(-2) [about 1/3 of a (100) monolayer]. When Si is introduced at GaAs- on-AlAs interfaces, the Al(2p)-to-Ga(3d) energy distance is observed t o increase for both polar and nonpolar interface orientations. The ins ertion of Si at GaAs/GaAs(110) homojunctions modifies the Line shape o f the Ga(Sd) and As(3d) peaks, resembling the changes previously repor ted for the (100) orientation. The results on polar junctions previous ly obtained were generally interpreted as band-offset changes, which w ould be related according to the ''interface microscopic capacitor'' p icture with the polar nature of the interface. The PES results hen pre sented are difficult to reconcile with such a model because of the sim ilar behavior shown by polar and nonpolar interfaces. Instead,they can be understood within an ''overlayer band bending'' interpretation. [S 0163-1829(98)01519-7].