A normally OFF hydrogen-terminated diamond (H-terminated diamond) field-effect transistor (FET) has been successfully achieved with Ti/TiO_x gate materials. A 5-nm Ti film was deposited on H-terminated diamond by electron beam evaporation technique and then it was thermally oxidized in air at 120 °C for 10 h to form Ti/TiO_x, which was confirmed by X-ray photoelectron spectroscopy. The threshold voltage of H-terminated diamond FET is −0.14 V at ${V}_{DS}$ of −8 V, indicating a normally OFF operation. The normally OFF property could be attributed to the difference of work difference between Ti and H-terminated diamond, which may deplete the hole carriers in H-terminated diamond 2-D hole gas (2DHG) conduction channel. The maximum mobility of H-terminated diamond FET is 313 cm²/Vs at ${V}_{GS}$ of −0.2 V. And, the fixed negative charge density is $3.37 \times 10 _{11}$ cm⁻². The results demonstrate that Ti/TiO_x H-terminated diamond FET is a good solution to fabricate normally OFF device with a simple fabrication process, undamaged 2DHG channel, and uncontaminated interface between Ti and TiO_x gate materials, which may promote the development of normally OFF H-terminated diamond FET.

中文翻译：

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具有 Ti/TiOₓ 栅极材料的常关断氢端接金刚石场效应晶体管

使用 Ti/TiO 成功实现了常关断氢端金刚石（H 端金刚石）场效应晶体管（FET）_X门材料。通过电子束蒸发技术在 H 端金刚石上沉积 5 nm Ti 薄膜，然后在空气中在 120 °C 下热氧化 10 h，形成 Ti/TiO_X，这已被 X 射线光电子能谱证实。H 端接金刚石 FET 的阈值电压为 -0.14 V at ${V}_{DS}$ −8 V，表示正常关闭操作。常关特性可能归因于Ti和H端金刚石之间的功差差异，这可能会耗尽H端金刚石二维空穴气体（2DHG）传导通道中的空穴载流子。H 端接金刚石 FET 的最大迁移率为 313 cm ² /Vs at ${V}_{GS}$ -0.2 V。并且，固定负电荷密度为 $3.37 \times 10 _{11}$ 厘米^-2。结果表明，Ti/TiO_X H 端接金刚石 FET 是制造常关器件的良好解决方案，具有简单的制造工艺、未损坏的 2DHG 通道以及未受污染的 Ti 和 TiO 之间的界面_X 栅极材料，这可能会促进常关 H 端接金刚石 FET 的发展。