Hydrolyzation oxidation of AlxGa1−xAs-AlAs-GaAs quantum well heterostructures and superlattices

Abstract

Data are presented on the conversion (selective conversion) of high-composition (AlAs)x(GaAs)1−x layers, e.g., in AlxGa1−xAs-AlAs-GaAs quantum well heterostructures and superlattices (SLs), into dense transparent native oxide by reaction with H2O vapor (N2 carrier gas) at elevated temperatures (400 °C). Hydrolyzation oxidation of a fine-scale AlAs(LB)-GaAs(Lz) SL (LB +Lz≲100 Å), or random alloy AlxGa1−xAs (x≳0.7), is observed to proceed more slowly and uniformly than a coarse-scale ‘‘alloy’’ such as an AlAs-GaAs superlattice with LB + Lz≳200 Å.

Birefringence evaluation of multimode multilayer AlGaAs/AlAs waveguides

“…9 In general, due to form birefringence, the field in low-index layers is higher for TM than for TE polarization. 3,6,10 It is therefore expected that by selectively lowering the refractive indices of thin AlAs layers, the effective indices of TM modes decrease more than TE.…”

Photonic crystals in the optical regime — past, present and future

“…A lattice produced by selective oxidation maintains the physical integrity of the material and produces an`all-solida microstructure. The oxidation technique was "rst proposed in the early 1990's [40] as a way of converting AlAs (or AlGaAs with a high Al-content, generally Al '80%) into a thermodynamically stable oxide. The process involves placing the sample into a steam environment at 400}4503C and produces an oxide with two desirable qualities: (a) The oxide is a good electrical insulator, which is the reason for its use as a current-blocking layer…”

“…We have observed an erosion rate of only 3 nm/min for a layer of oxidised 80% x-fraction AlGaAs, which is a considerable improvement over externally deposited dielectrics. The oxidation is carried out at 400}4503C in a wet steam atmosphere, a process that has been widely studied, mainly for current aperturing in vertical cavity surface-emitting lasers (VCSELs) [39,40]. Despite this obvious improvement in erosion rate, AlO V masks have not been widely used, in part because they have to be designed into the epitaxial material structure.…”

Comparative analysis of lasing performance of oxide-confined and proton-implanted vertical-cavity surface-emitting diode lasers

“…In modern GaAsbased VCSELs, it is usually carried out by oxide Al x O y apertures [2] created in AlAs-rich (AlGa)As layers by radial wet oxidation [3,4]. In such oxide-confined (OC) VCSELs [5][6][7][8], the apertures may influence both the radiation field [because of much lower (∼1.6) refractive index of Al x O y than those of semiconductor layers (over 3)] and current spreading (because of high electrical resistivity of Al x O y ).…”