No abstract

No abstract

Interdiffusion of Al and Ga in Al0.4Ga0.6As/GaAs and Al0.3Ga0.2In0.5P/Ga0.6In0.4P quantum wells has been investigated by measuring the photoluminescence of samples annealed at temperatures from 850 to 1065 °C with and without an SiO2 cap. At 1000 °C under an SiO2 cap, the Al–Ga interdiffusion coefficient is found to be at least two orders of magnitude larger for an AlGaAs/GaAs quantum well compared to an AlGaInP/GaInP quantum well within the same sample. By comparing calculated photoluminescence shifts with measured values, an activation energy of 4.5 eV is found for the Al–Ga interdiffusion in an AlGaAs/GaAs quantum well under an SiO2 cap.

The growth of GaAs irradiated with ultraviolet laser light in a metalorganic chemical vapor deposition reactor has been investigated. Growth rate enhancements of up to 15% were observed at 450 °C by illuminating the substrate with no more than 13 mJ/cm2 of KrF laser (248 nm) radiation. For 5-eV photons, arsine is virtually transparent, while the trimethylgallium (TMG) photoabsorption cross section is approximately 10−19 cm2. Data acquired with and without the optical beam impinging on the substrate are well described by the Langmuir–Hinshelwood model, and the results point to photodissociation of adsorbed TMG as the origin of the growth rate enhancement. Nearly identical experiments carried out at 351 nm (XeF) corroborate this conclusion since no measurable increase in growth rate was observed at this wavelength, where both arsine and TMG photoabsorption is negligible. Conversely, significant improvement in surface morphology for samples grown below 700 °C is observed with ultraviolet laser irradiation of the substrate at each of the wavelengths investigated (193, 248, and 351 nm). Smooth and specular surfaces are obtained with substrate temperatures as low as 550 °C and at fluences well below those which induce a significant rise in the surface temperature.

Articles you may be interested inComparison of the carrier induced refractive index, gain, and linewidth enhancement factor in quantum dot and quantum well lasers