The optical functions of ␤-Ga 2 O 3 thin films have been determined by ellipsometry from 0.74-5 eV. Several electron-beam evaporated and rf magnetron sputtered films of different thicknesses were investigated using a multisample technique. Refractive index values comparable to those of bulk material are found. Cauchy dispersion model fits yield a high-frequency dielectric constant ⑀ ϱ of 3.57. Above 4.7 eV a direct absorption edge is observed.

We propose and demonstrate a novel approach to the coating of semiconductor laser facets. In this approach, processed semiconductor lasers are cleaved in a high-vacuum system immediately followed by coating of the vacuum-exposed facet with a very thin Si layer (≤100 Å) and a large band gap dielectric (Al2O3) layer. The Si layer is sufficiently thin to avoid the formation of quantized bound states in the Si. GaAs coated with thin Si and Al2O3 have a higher luminescence yield and a lower surface recombination velocity than bare GaAs surfaces as well as GaAs surfaces coated with Al2O3 only. A surface recombination velocity of 3×104 cm/s has been obtained using a modified dead layer model for the Si/Al2O3 sample. It is also shown that lasers which are cleaved in vacuum and subsequently coated with Si and Al2O3 have improved properties including an increased threshold for catastrophic optical damage.

High-quality single-crystal Sc 2 O 3 films a few nanometer thick have been grown epitaxially on Si ͑111͒ despite a huge lattice mismatch. The films were electron-beam evaporated from a Sc 2 O 3 target. Structural and morphological studies were carried out by x-ray diffraction and reflectivity, atomic force microscopy, high-resolution transmission electron microscopy, and medium-energy ion scattering, with the initial epitaxial growth monitored by in situ reflection high-energy electron diffraction. The films have the cubic bixbyite phase with a remarkably uniform thickness and high structural perfection. The film surfaces are very smooth and the oxide/Si interfaces are atomically sharp with a low average roughness of 0.06 nm. The films are well aligned with the Si substrate with an orientation relationship of Si͑111͒ ʈ Sc 2 O 3 ͑111͒, and an in-plane expitaxy of Si͓110͔ ʈ Sc 2 O 3 ͓101͔.

Articles you may be interested inSelf-aligned inversion-channel In 0.2 Ga 0.8 As metal-oxide-semiconductor field-effect transistor with molecular beam epitaxy Al 2 O 3 / Ga 2 O 3 ( Gd 2 O 3 ) as the gate dielectric J. Vac. Sci. Technol. B 29, 03C122 (2011); 10.1116/1.3565057 Molecular beam epitaxy growth of InAs and In 0.8 Ga 0.2 As channel materials on GaAs substrate for metal oxide semiconductor field effect transistor applications Ga 2 O 3 grown on GaAs by molecular beam epitaxy for metal oxide semiconductor field effect transistors

Growth and physical properties of Ga 2 O 3 thin films on GaAs(001) substrate by molecular-beam epitaxy Ga 2 O 3 ͑Gd 2 O 3 ͒-GaAs heterostructures in situ fabricated using a multichamber ultrahigh vacuum ͑molecular beam epitaxy͒ system were studied by x-ray reflectivity measurement and high-resolution transmission electron microscopy. The oxide-GaAs interfaces were found to be very smooth with the roughness no more than 1 nm. Moreover, an interfacial roughness as small as one atomic layer of GaAs ͑0.33 nm͒ was observed using x-ray reflectivity.