Crystalline and electrical characteristics of C 60-doped GaAs films

Abstract

C 60 uniformly doped and δ-doped GaAs layers are grown by migration enhanced epitaxy method. Crystalline and electrical characteristics of the layers are investigated by reflection high energy electron diffraction, X-ray diffraction and capacitance–voltage ( C– V) measurements. C 60 high-concentration doping is found to introduce 2D defects, and X-ray diffraction pole-figure measurements show that the rotational domains appear predominantly on {1 1 1}A plane. This indicates that C 60 molecules are mainly incorporated on the dangling bonds of Ga atoms due to the high binding energy between C 60 molecules and Ga atoms. C 60 uniformly doped GaAs layers show highly resistive characteristics, suggesting that C 60 molecules cannot be decomposed into isolated C atoms in the GaAs lattice, and they behave as if they were electron traps or strong recombination centers. C– V profiles of Cr–Au/C 60 δ-doped GaAs Schottky diode suggest that C 60 molecules in GaAs lattice produce electron traps which can be charged or discharged by applied electrical field.