Statistical analysis of current-voltage characteristics in Au/Ta_2O_5/n-GaN Schottky barrier heterojunction using different methods

摘要

We report on the influence of incorporation of Ta_2O_5 thin film at the interface of Au/GaN by means of e-beam evaporation technique. The fabricated Au/Ta_2O_5/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 Φ_(bo), n and R_S values are evaluated using Ⅰ-Ⅴ curves at room temperature. The statistical distribution analysis provides the mean 'Φ_(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, Φ_(bo) and R_S from Ⅰ-Ⅴ characteristics of Au/Ta_2O_5/n-GaN MIS junctions and are in well agreement with each other. Under forward-bias, the fabricated Au/Ta_2O_5/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/Ta_2O_5/n-GaN. In conclusion, the obtained superior rectification ratio of 6.06 × 10~4 and higher SBH of 0.87 eV was ascribed to the purposefully deposited undoped GaN buffer layer between epitaxial GaN and sapphire substrate.