Mechanical Properties of Epilayers of Metastable α- and ε-Ga2O3 Phases Studied by Nanoindentation

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

“…Unfortunately, the PEALD reactors are more complex than the thermal ALD reactors. Moreover, the ALD cycle durations exceeding 15 s, that is, significantly longer than those of our thermal GaI 3 –O 3 process, have been used for PEALD of Ga 2 O 3 . ,, At the same time, the GPC values obtained for the GaI 3 –O 3 process (Figure c and Table ) are comparable to or even higher than those reported for PEALD allowing low-temperature growth of crystalline Ga 2 O 3 . ,, Therefore, the GaI 3 –O 3 ALD process that differently from many others, yields crystalline films at relatively low T G on substrates, which do not support epitaxial growth, has considerable advantages in deposition of high-density Ga 2 O 3 films, containing phases with superior mechanical properties and high-permittivity. , This is of particular importance in the deposition of thin films on 3 d -profiled substrates where the limited lifetimes of plasma-activated species might restrict the conformal surface coating in PEALD. Deposition of κ­(ε)-Ga 2 O 3 films with ferroelectric properties and high permittivity for memory devices, wide-gap α-Ga 2 O 3 layers for microelectronic devices, and κ­(ε)-Ga 2 O 3 and α-Ga 2 O 3 coatings with high hardness are some possible applications of the process developed in this work.…”

“…In earlier studies, the thin films containing crystalline Ga 2 O 3 have been grown on single crystal α-Al 2 O 3 , ,,− ,,,, GaN, SiC, and Si(111), and on α-Cr 2 O 3 , indium–tin oxide, and Al 2 O 3 buffer layers deposited on single crystal α-Al 2 O 3 , , yttrium stabilized zirconia, and Si(1 1 1), respectively. In the case of most thin-film deposition techniques used for the deposition of crystalline Ga 2 O 3 , substrate temperatures ≥500 °C have been needed for this purpose. ,,− ,,,, The plasma-enhanced ALD (PEALD) method that has enabled the growth of a mixture of α- and β-Ga 2 O 3 at T G ≥ 190 °C and α-Ga 2 O 3 at T G ≥ 250 °C on α-Al 2 O 3 has been a notable exception from this rule. However, for the deposition of crystalline films on substrates that do not support epitaxial growth, markedly higher T G or application of in situ Ar plasma annealing in PEALD (Table ) has been inevitable .…”

“…However, the possibilities to obtain thin films containing other phases that are energetically less favorable are also of marked interest. For example, when compared with β-Ga 2 O 3 , the α-Ga 2 O 3 phase seems to be more suitable for solid-state electronic devices of emerging applications because this phase has a larger bandgap, breakdown voltage, and dielectric constant than β-Ga 2 O 3 . , In addition, the hardness values of α-Ga 2 O 3 and ε­(κ)-Ga 2 O 3 are higher than that of β-Ga 2 O 3 …”

Optical properties of Ga2O3 thin films grown by atomic layer deposition using GaI3 and O3 as precursors

“…Gallium oxide (Ga 2 O 3 ) has attracted marked interest as a promising material for high-voltage electronic devices, [1][2][3] high electron-mobility transistors, 4 resistive switching memories, 5,6 solar-blind radiation detectors, [7][8][9] and scintillators. 10 Gallium oxide has also been studied as a relatively hard material 11,12 that can, therefore, be used in protective coatings. Furthermore, possibilities for application of Ga 2 O 3 for surface passivation of silicon solar cells have been recently investigated.…”