Nanopatterning Induced Si Doping in Amorphous Ga₂O₃ for Enhanced Electrical Properties and Ultra-Fast Photodetection

Ga₂O₃ has emerged as a promising material for the wide-bandgap industry aiming at devices beyond the limits of conventional silicon. Amorphous Ga₂O₃ is widely being used for flexible electronics, but suffers from very high resistivity. Conventional methods of doping like ion implantation require high temperatures post-processing, thereby limiting their use. Herein, an unconventional method of doping Ga₂O₃ films with Si, thereby enhancing its electrical properties, is reported. Ion-beam sputtering (500 eV Ar⁺) is utilized to nanopattern SiO₂-coated Si substrate leaving the topmost part rich in elemental Si. This helps in enhancing the carrier conduction by increasing n-type doping of the subsequently coated 5 nm amorphous Ga₂O₃ films, corroborated by room-temperature resistivity measurement and valence band spectra, respectively, while the nanopatterns formed help in better light management. Finally, as proof of concept, metal-semiconductor-metal (MSM) photoconductor devices fabricated on doped, rippled films show superior properties with responsivity increasing from 6 to 433 mA W^-1 while having fast detection speeds of 861 µs/710 µs (rise/fall time) as opposed to non-rippled devices (377 ms/392 ms). The results demonstrate a facile, cost-effective, and large-area method to dope amorphous Ga₂O₃ films in a bottom-up approach which may be employed for increasing the electrical conductivity of other amorphous oxide semiconductors as well.