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Diamond exhibits large application potential in the field of power electronics, owing to its excellent and desirable electronic properties. However, the main obstacles to its development originate from the small‐sized single‐crystal wafers and the instability of the electrical conductivity. This work presents a metal‐oxide‐semiconductor field‐effect transistor (MOSFET) on a diamond substrate derived from a five‐inch (110) highly preferred polycrystalline diamond film. The MOSFETs with excellent performance are fabricated by combining an H‐terminated channel and an epitaxially grown boron‐doped layer as the source/drain contacts of the diamond devices. According to the electrical statistical results of ≈110 devices on the polycrystalline diamond substrate, 44% of devices show normally‐off operation with a maximum current density of 400 mA mm−1, while 56% of devices demonstrate normally‐on operation with a maximum current density of 525 mA mm−1. The normally‐off characteristics are more related to the higher amounts of nitrogen concentration than the grain boundaries. The stable boron‐doped source and drain provide a high concentration of holes, which facilitate transport in the surface p‐type channel induced by the H‐termination. The characteristics of the MOSFETs are inspiring for the fabrication of complementary inverter circuits on large diamond wafers. [ABSTRACT FROM AUTHOR]

This letter reports the successful demonstration of large-current and high-voltage (001) vertical-type two-dimensional hole gas (2DHG) diamond trench metal-oxide-semiconductor field-effect transistors (MOSFETs) with a p−-drift layer. The fabricated transistor demonstrated a maximum drain current density of 210 mA/mm, a field-effect-mobility of 61 cm2V−1s−1, and a specific on-resistance of 23 $\text{m}\Omega $ cm2. Moreover, a high breakdown voltage of 580 V with a gate-drain length of 10 $\mu \text{m}$ was obtained, which is the highest value reported for a vertical-type diamond MOSFET to date. These characteristics indicate that a vertical-type diamond MOSFET using a p−-drift layer may be used to realize a p-channel power device with a high breakdown voltage and low on-resistance. [ABSTRACT FROM AUTHOR]

Diamonds are highly favored materials in high-temperature and high-power operations owing to their excellent characteristics, and diamond p-channel field-effect transistors (p-FETs) considerably aid in the improvement of CMOS technology, providing high performance, which is essential for inverter operations. This study demonstrates a low ON-resistance (001) vertical-type two-dimensional hole gas (2-DHG) diamond metal–oxide–semiconductor field-effect transistor (MOSFET) with a trench gate structure. The active area of the device reduced after introducing a trench gate structure that can significantly improve the device integration and high-current operation. The maximum drain current density (ID) exceeds 20 kA/cm2 at VDS = −50 V and VGS = −20 V, which is the highest value obtained for (001) vertical-type diamond MOSFETs. This vertical-type diamond trench MOSFET can obtain the lowest ON-resistance (RONS) of 2.5 mΩ⋅ cm2, which is comparable to that of SiC and GaN vertical-type n-channel FETs (n-FETs). It can be potentially used as a p-channel power FET in a complementary inverter. Furthermore, this study demonstrates that the trench contact depth to the p+ diamond substrate significantly impacts the static characteristics of a device using the ATLAS device simulation. This result significantly contributes to the improvement of the rising drain current in the low-voltage region of the vertical-type diamond FET, which can be used in the future as p-channel power devices for the next generation of complementary inverters using GaN or SiC MOSFETs as n-channels. [ABSTRACT FROM AUTHOR]

We fabricated (001) vertical diamond metal-oxide-semiconductor field-effect transistors (MOSFETs) with oxidized Si-terminated (C–Si–O) diamond channels on the surfaces and trench sidewalls. The C–Si–O diamond surface is approximately 1.0 eV weaker in negative electron affinity than the hydrogen-terminated (C–H) diamond surface, resulting in a smaller valence band bending between the interface of C–Si–O diamond surface and Al 2 O 3 , and larger the difference between the energy values of the fermi level and the valence band on the top (E F − E V), and the threshold voltage (V th) shifts in the negative direction. As a result, the maximum drain current density was 108 mA/mm, the V th was −9.0 V. Compared with conventional vertical diamond FETs using a C–H channel, the V th was shifted more than 20 V in the negative direction to reach normally-off mode. The normally-off operation was achieved while maintaining high current density, which is the first case of normally-off operation that has been observed in vertical diamond FETs. In, addition, it was confirmed that the diode functions as a freewheeling diode by adding a reverse drain voltage and allowing current to flow, and the change of current-voltage characteristics was also investigated by swapping the source and drain positions and performing measurements. [Display omitted] • P-channel vertical diamond MOSFETs are essential to realize high-power high-speed complementary inverters. • The 2DHG can be induced independent of the surface orientation. • Oxidized Si-terminated (C–Si–O) diamond surface can achieve normally-off operation at high drain current density. • High current density of 108 mA/mm and normally-off operation of −9.0 V were obtained. [ABSTRACT FROM AUTHOR]