TEMPERATURE-DEPENDENT COMPENSATION OF ZN-DOPANT ATOMS BY VACANCIES INIII-V SEMICONDUCTOR SURFACES

Scanning tunneling microscopy is used to study the compensation of Zn- dopant atoms by surface vacancies on InP and GaAs(110) surfaces as a f unction of the annealing time and temperature. An attractive interacti on is observed between negatively charged Zn atoms and positively char ged anion vacancies. Uncharged Zn-vacancy defect complexes are formed and their structure is analyzed. The concentration of the complexes in creases with the vacancy concentration. Simultaneously the concentrati on of charged Zn decreases. The total observable Zn concentration is f ound to be the sum of the concentration of isolated charged Zn atoms a nd of the concentration of the defect complexes. This sum is constant at low temperatures, but decreases at 480 K. The observations are expl ained by the formation of subsurface defect complexes at higher temper atures and surface complexes at low temperatures. (C) 1996 American Va cuum Society.