High-k ZrO₂/Al₂O₃ bilayer on hydrogenated diamond: Band configuration, breakdown field, and electrical properties of field-effect transistors Available to Purchase

A band configuration of a high-k ZrO₂/Al₂O₃ bilayer on hydrogenated diamond (H-diamond), a breakdown field (E_B) of the ZrO₂/Al₂O₃ bilayer, and an effect of gate-drain distance (d_G-D) on electrical properties of ZrO₂/Al₂O₃/H-diamond metal-insulator-semiconductor field-effect transistors (MISFETs) have been investigated. The Al₂O₃ and ZrO₂ layers are successively deposited on H-diamond by atomic layer deposition (ALD) and sputtering-deposition (SD) techniques, respectively. The thin ALD-Al₂O₃ buffer layer with 4.0 nm thickness plays a role in protecting the H-diamond surface from being damaged by the plasma discharge during SD-ZrO₂ deposition. The ZrO₂/Al₂O₃ heterojunction has a type I band structure with valence and conduction band offsets of 0.6 ± 0.2 and 1.0 ± 0.2 eV, respectively. The valence band offset between ZrO₂ and H-diamond is deduced to be 2.3 ± 0.2 eV. The E_B of the ZrO₂/Al₂O₃ bilayer is measured to be 5.2 MV cm⁻¹, which is larger than that of the single ZrO₂ layer due to the existence of the ALD-Al₂O₃ buffer layer. The dependence of d_G-D on drain-source current maximum (I_DS,max), on-resistance (R_ON), threshold voltage (V_TH), and extrinsic transconductance maximum (g_m,max) of the MISFETs has been investigated. With increasing d_G-D from 4 to 18 μm, the absolute I_DS,max decreases from 72.7 to 40.1 mA mm⁻¹, and the R_ON increases linearly from 83.3 ± 5 to 158.7 ± 5 Ω mm. Variation of V_TH values of around 1.0 V is observed, and the g_m,max is in the range between 8.0 ± 0.1 and 13.1 ± 0.1 mS mm⁻¹.