High Performance of Normally‐On and Normally‐Off Devices with Highly Boron‐Doped Source and Drain on H‐Terminated Polycrystalline Diamond

Abstract

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.

Hydrogen-Terminated Single Crystal Diamond MOSFET with a Bilayer Dielectric of Gd2O3/Al2O3

“…Diamond has many excellent electrical properties, such as an ultra-wide band gap (5.45 eV), high breakdown voltage (>10 MV/cm), high carrier mobility (electron: 4500 cm 2 /Vs, hole: 3800 cm 2 /Vs), the highest thermal conductivity (22 W/K • cm), effective resistance, etc. [1][2][3][4][5][6][7][8][9][10]. All of these characteristics make a diamond a promising semiconductor material.…”

“…In the selection of the new high-k dielectric layer, the first point is that the k value of the dielectric layer should be high and thermodynamically have good stability to ensure that the device can work under harsh conditions; its band bias as an insulator whose contact with the semiconductor should exceed 1 eV can reduce carrier injection; the dielectric layer in the MOS structure should form a good electrical interface with the semiconductor; and finally, the dielectric layer should have lower volume electrical defects. Gadolinium oxide (Gd 2 O 3 ) is a promising dielectric for the H-diamond MOSFET with a high dielectric constant (9)(10)(11)(12)(13)(14) and large band gap (5.3 eV) [24][25][26]. In addition, due to its stable properties, the dielectric layer and the semiconductor film base were better bonded with a lower density of interfacial states, and the leakage current of the device was small, which is now widely used in dynamic random memory and other fields.…”