High-dielectric-constant Ta2O5/n-GaN metal-oxide-semiconductor structure

L. W. Tu, W. C. Kuo, K. H. Lee, P. H. Tsao, C. M. Lai, A. K. Chu, J. K. Sheu

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76 引文 斯高帕斯(Scopus)


High-dielectric-constant Ta2O5 has been grown on the n-GaN epifilm by rf magnetron sputtering. Photoluminescence measurement has been performed to compare the luminescence intensity with and without the dielectrics. Threefold increase in intensity is obtained, and a surface recombination velocity is estimated to be 3×104 cm/s as an upper limit using a modified dead-layer model. A metal-oxide-semiconductor structure has been fabricated with Al on n-GaN as the ohmic contact and on Ta2O5 as the gate metal. Capacitance-versus-voltage characteristics have been measured. The doping concentration obtained from the depletion regime is compared with the result of Hall measurement, which is 7.0×1016 cm-3. The flat-band voltage is obtained from the high-frequency data, and the effective oxide charge number density is calculated as 4.1×1012 cm-2. Indication of strong inversion appears at low reverse bias due to the high dielectric constant of Ta2O5, and matches closely with calculated values. Hysteresis is observed and ascribed to positive mobile charges derived as 2.1×1012 cm-2. The capacitance dependence on the frequency and the leakage current are discussed.

頁(從 - 到)3788-3790
期刊Applied Physics Letters
出版狀態Published - 2000 十二月 4

All Science Journal Classification (ASJC) codes

  • 物理與天文學(雜項)


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