Structures and defects in arsenic-ion-implanted GaAs films annealed at high temperatures

Abstract

The structures and defects are studied in arsenic-ion-implanted GaAs(As+-GaAs) films annealed at temperatures higher than 600 degrees C by using transmission electron microscopy, deep level transient spectroscopy, temperature-dependent conductance, and photoluminescence. The estimated concentration of arsenic precipitates in films decreases from similar to 4x10(16) cm(-3) to similar to 6x10(15) cm(-)3 and the corresponding size increases from similar to 3 to similar to 10 nm as the annealing temperature increases from 600 to 800 degrees C. A defect with an energy level at about 0.3 eV from the band edge is found and its concentration increases with the increasing annealing temperatures. The electrical transport of free carriers is replaced by hopping conduction, through the defect band at about 0.26 eV below conduction band, when the film is annealed at temperature 800 degrees C. It indicates that during high-temperature annealing the defect of the arsenic and gallium vacancies due to the diffusion of As and Ga atoms is the dominant factor to change its electrical and structural properties. (C) 1997 American Institute of Physics.