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

GaO has emerged as a promising material for the wide-bandgap industry aiming at devices beyond the limits of conventional silicon. Amorphous GaO 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 GaO films with Si, thereby enhancing its electrical properties, is reported. Ion-beam sputtering (500 eV Ar) is utilized to nanopattern SiO-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 GaO 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 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 GaO films in a bottom-up approach which may be employed for increasing the electrical conductivity of other amorphous oxide semiconductors as well.