Diamond field effect transistors with a high-dielectric constant Ta2O5 as gate material

作者：Liu J W^*; Liao M Y; Imura M; Watanabe E; Oosato H; Koide Y

来源：Journal of Physics D: Applied Physics , 2014, 47(24): 245102.

DOI：10.1088/0022-3727/47/24/245102

• diamond
• transistor
• high-k
• Ta2O5

A Ta2O5/Al2O3 bilayer gate oxide with a high-dielectric constant (high-k) has been successfully applied to a hydrogenated-diamond (H-diamond) metal-insulator-semiconductor field effect transistor (MISFET). The Ta2O5 layer is prepared by a sputtering-deposition (SD) technique on the Al2O3 buffer layer fabricated by an atomic layer deposition (ALD) technique. The ALD-Al2O3 plays an important role to eliminate plasma damage for the H-diamond surface during SD-Ta2O5 deposition. The dielectric constants of the SD-Ta2O5/ALD-Al2O3 bilayer and single SD-Ta2O5 are as large as 12.7 and 16.5, respectively. The k value of the single SD-Ta2O5 in this study is in good agreement with that of the SD-Ta2O5 on oxygen-terminated diamond. The capacitance-voltage characteristic suggests low interfacial trapped charge density for the SD-Ta2O5/ALD-Al2O3/H-diamond MIS diode. The MISFET with a gate length of 4 mu m has a drain current maximum and an extrinsic transconductance of -97.7 mA mm(-1) (normalized by gate width) and 31.0 +/- 0.1 mS mm(-1), respectively. The effective mobility in the H-diamond channel layer is found to be 70.1 +/- 0.5 cm(2) V-1 s(-1).

• 出版日期2014-6-18