Effect of O2 plasma exposure time during atomic layer deposition of amorphous gallium oxide

Abstract

Amorphous gallium oxide thin films were grown by plasma-enhanced atomic layer deposition on (100) silicon substrates from trimethylgallium Ga(CH3)3 precursor and oxygen plasma. At 200 °C, the growth per cycle is in the range of 0.65–0.70 Å for O2 plasma exposure times ranging from 3 up to 30 s during each cycle. The effect of O2 plasma exposure times on the interfacial SiOx regrowth and the electrical properties was investigated. In situ spectroscopic ellipsometry shows that the SiOx regrowth occurs during the first three cycles and is limited to 0.27 nm for plasma times as long as 30 s. Increasing the O2 plasma exposure during each ALD cycle leads to a drastic decrease in the leakage current density (more than 5 orders of magnitude for 30 nm films), which is linked to the suppression of oxygen vacancy states as evidenced by spectroscopic ellipsometry. Interestingly, an increase in the dielectric constant with increasing O2 plasma exposure time is observed, reaching a value of εr∼14.2, larger than that of single crystalline β-Ga2O3. This study highlights the crucial role of oxygen plasma exposure time in the control and tuning of the electrical properties of amorphous gallium oxide films.

Growth characteristics and properties of Ga2O3 films fabricated by atomic layer deposition technique

“…62 For the as-deposited Ga 2 O 3 films, the C 1s peak at 285–286 eV was attributed to hydrocarbon species with C–H or C–C bonds, while the peak at ∼290 eV was attributed to oxidized carbonaceous species with C–O–C or O–CO bonds, both of which disappeared after sputtering for 15 min. 99…”

“…The growth rate increased initially with increasing TEG dose, but then remained at 0.062 nm per cycle when the TEG pulse time was longer than 0.1 s. 71 Kro ¨ncke et al found that 3 s was the lower limit for O 2 plasma pulse, and the growth rate was greatly reduced at a shorter time and limited by the low flux of the oxygen species. 99 Ding's group found that 0.1 s TMG was enough to reach saturation, and the growth rate was almost independent on the pulse duration of 0.1 to 0.2 s. The growth rate increased with O 2 plasma duration and was saturated at the pulse time of 18 s. 63 Donmez et al reported that 0.015 s duration was enough for TMG dose and 10 s for O 2 duration; five seconds of Ar flow was sufficient for complete the purging of excess precursors and gaseous byproducts. 61 As shown in Fig.…”

“…62 For the as-deposited Ga 2 O 3 films, the C 1s peak at 285-286 eV was attributed to hydrocarbon species with C-H or C-C bonds, while the peak at This journal is © The Royal Society of Chemistry 2022 B290 eV was attributed to oxidized carbonaceous species with C-O-C or O-CQO bonds, both of which disappeared after sputtering for 15 min. 99 The sputtering process can also affect the Ga/O ratio in Ga 2 O 3 films. The Ga/O ratio was increased from 0.71 to 0.76 after Ar + sputtering on the Ga 2 O 3 surface, which could be ascribed to oxygen vacancies.…”

2D Amorphous GaOX Gate Dielectric for β-Ga2O3 Field-Effect Transistors

“…The atomic-scale thickness and low-cost fabrication of 2D GaO X , combined with the desirable dielectric properties of conventional GaO X films, such as an ultrawide bandgap greater than 5 eV , and a sizable static dielectric constant of 10–14, , make 2D GaO X a promising candidate for use as a high-quality insulator for MISFET architectures. In this study, a large-area 2D GaO X dielectric with a controllable nanometer-scale thickness via stacking was fabricated using the liquid-gallium squeezing technique and combined with an exfoliated β-Ga 2 O 3 FET to form a novel 2D GaO X /β-Ga 2 O 3 MISFET.…”

Atomic Layer Deposition of Ga2O3 from GaI3 and O3: Growth of High-Density Phases

“…Possibilities to improve high-performance power-electronic devices used in trains, charging infrastructure of electrical cars, grid-scale energy storage, motor controls, and different military systems are constantly studied. Owing to its wide bandgap and large breakdown field, gallium oxide (Ga 2 O 3 ) could be a promising material for these applications. − Moreover, Ga 2 O 3 is a prospective material for gas sensors, , solar-blind UV detectors, X-ray detectors, and solar cells. − , …”