THERMAL FORMATION OF ZN-DOPANT-VACANCY DEFECT COMPLEXES ON INP(110) SURFACES

The thermal formation of Zn-dopant-vacancy defect complexes is studied as a function of annealing time and temperature between 293 and 480 K on InP(110) surfaces using scanning tunneling microscopy. The geometr ic and electronic structure as well as the concentrations of isolated dopant atoms, phosphorus monovacancies, and vacancy-Zn defect complexe s are found to be related to each other. An attractive interaction bet ween the vacancies and Zn atoms is found. The vacancies and Zn-dopant atoms can compensate each other's charge and form uncharged complexes. The formation of these compensated defect complexes strongly decrease s the concentration of electrically active Zn atoms. The total observa ble Zn concentration in the surface layers remains constant with time at temperatures up to 415 K. Only defect complexes consisting of a sur face vacancy and a subsurface dopant atom are formed. At 480 K the obs ervable Zn concentration decreases, however, because defect complexes consisting of a subsurface vacancy and a Zn atom are formed.