Doping dependence of the barrier height and ideality factor of Au/n-GaAs schottky diodes at low temperatures

Abstract

The barrier height and ideality factor of Au/n-GaAs Schottky diodes grown by metal-organic vapor-phase epitaxy (MOVPE) on undoped and Si-doped n-GaAs substrates were determined in the doping range of 2.5×10¹⁵-1×10¹⁸ cm^-3 at low temperatures. The thermionic-emission zero-bias barrier height for current transport decreases rapidly at concentrations greater than 1×10¹⁸ cm^-3. The ideality factor also increases very rapidly at higher concentration and at lower temperature. The results agree quite well with thermionic field emission (TFE) theory. The doping dependence of the barrier height and the ideality factor were obtained in the concentration range of 2.5×10¹⁵-1.0× 10¹⁸ cm^-3 and the results are well described using TFE theory. An excellent match between the homogeneous barrier height and the effective barrier height was observed which supports the good quality of the GaAs film. The observed variation in the zero-bias barrier height and the ideality factor can also be explained in terms of barrier height inhomogeneities in the Schottky diode.