Diamond surfaces terminated with a silicon layer (C–Si) can induce a two-dimensional hole gas (2DHG) layer at the insulator/diamond interface

enabling the realization of p-channel metal–oxide-semiconductor field-effect transistors (MOSFETs). Through two primary fabrication routes—namely

SiO

2

annealing in a reducing atmosphere and silicon molecular beam deposition (MBD) at high temperatures—stable oxidized silicon-terminated (C–Si–O) and C–Si diamond channels have been realized. These channels facilitate normally-off p-channel FETs with threshold voltages (

V

TH

) ranging from −3 to −16 V and hole mobilities between 100 and 200 cm

2

/V·s. For instance

a (111)-oriented C–Si–O MOSFET with a

V

TH

of −5.6 V delivers an output current density of −311 mA/mm

whereas another MBD C–Si–O MOSFET with a varying source-to-drain distance (

L

SD

) shows a

ΔV

TH

shift whose magnitude is less than 0.2 V. This review provides a critical overview of the chemical structures

the formation methods

and operational mechanisms of C–Si–O diamond surfaces. It also summarizes recent progress in C–Si–O diamond electronic devices

with emphasis on device architectures

fabrication techniques

and electrical characteristics. Finally

key challenges and potential pathways toward the industrial adoption of this emerging technology are discuss

ed.