Crystalline and electrical characteristics of C60-doped GaAs films

C60 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 measurements. C60 high-concentration doping is found to introduce 2D defects, and X-ray diffraction pole-figure measurements show that the rotational domains appear predominantly on {111}A plane. This indicates that C60 molecules are mainly incorporated on the dangling bonds of Ga atoms due to the high binding energy between C60 molecules and Ga atoms. C60 uniformly doped GaAs layers show highly resistive characteristics, suggesting that C60 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 / C60 δ-doped GaAs Schottky diode suggest that C60 molecules in GaAs lattice produce electron traps which can be charged or discharged by applied electrical field