Statistical analysis of current-voltage characteristics in Au/Ta2O5/n-GaN Schottky barrier heterojunction using different methods

We report on the influence of incorporation of Ta2O5 thin film at the interface of Au/GaN by means of e-beam evaporation technique. The fabricated Au/Ta2O5/n-GaN MIS junctions have been analysed using I-V measurements and were extended to a voltage range of +/- 20 V. The Schottky diode parameters for instance Phi (bo), n and R-S values are evaluated using I-V curves at room temperature. The statistical distribution analysis provides the mean 'Phi (bo)' value of 0.85 eV with deviation of 0.00181 eV and mean value from 'n' is 1.36 with a normal deviation of 0.00562. Two important electrical parameters such as R-S and R-sh values are also extracted from I-V characteristics. Furthermore, Cheung, Norde, modified Norde, Hernandez and Chattopadhyay methods are used to evaluate the Schottky barrier parameters from I-V data. The comparison is made between the extracted electrical parameters such as n, Phi (bo) and R-S from I-V characteristics of Au/Ta2O5/n-GaN MIS junctions and are in well agreement with each other. Under forward-bias, the fabricated Au/Ta2O5/n-GaN MIS junction conduction mechanisms such as ohmic and SCL were found to be dominant at lower and higher voltage regimes, respectively. By fitting reverse-bias region of I-V curves, PF conduction mechanism was found to be dominant at the interfaces of Au/Ta2O5/n-GaN. In conclusion, the obtained superior rectification ratio of 6.06x10(4) and higher SBH of 0.87 eV was ascribed to the purposefully deposited undoped GaN buffer layer between epitaxial GaN and sapphire substrate.