LOW-TEMPERATURE METALORGANIC CHEMICAL-VAPOR-DEPOSITION OF AIN FOR SURFACE PASSIVATION OF GAAS

Aluminium nitride (AlN) thin films have been grown by low-temperature metalorganic chemical vapour deposition (MOCVD) to passivate GaAs. By utilizing hydrazine (N2H4), highly resistive amorphous-like AlN films were obtained at growth temperatures around 400 degrees C. At the AlN- GaAs interface, three deep trap levels were found: 0.6 eV (DL1) and 0. 9 eV (DL2) below the conduction band minimum and 0.5 eV (DL3) above th e valence band maximum. The number of DL1 levels was reduced by prepar ing As-dimer-stabilised surfaces of GaAs. The capture cross-sections a nd time constants of DL1-DL3 suggest that these levels originated from point defects, not from precipitates or disorder. Neither precipitati on nor reaction was detectable by Auger electron spectroscopy after an nealing at 900 degrees C for 20 min, indicating that the AlN-GaAs inte rfaces are thermally stable. These results demonstrate that these AlN films are applicable as capping films for processing GaAs as well as p assivation films.