Laser stimulated selective area growth of quantum dots

Abstract

We report on the selective area growth of InAs quantum dots on GaAs by ultraviolet (UV) laser stimulated organometallic vapor phase epitaxy. At the low substrate temperature of 435 °C, exposure to a 248.2 nm continuous wave laser beam enhances the InAs growth rate by approximately 30%, causing the transition from two-dimensional (2D) to 3D growth mode to occur in the laser stimulated region only. Photoluminescence spectra from the UV laser stimulated growth region show both wetting layer and quantum dot luminescence, whereas only the wetting layer peak is present in the spectra from the dark grown regions. A photoluminescence map shows good spatial agreement between the region exhibiting quantum dot luminescence and the UV stimulated spot size. Since no quantum dot peak shifts are detected, but the luminescence intensity increases towards the center of the region stimulated with the Gaussian UV beam, we conclude that the island density rather than island size distribution is influenced by the UV intensity.

Real-time monitoring of InAs/GaAs quantum dot growth using ultraviolet light scattering

“…We note also that adlayer photolysis has been observed using 248 nm laser light during growth of InAs dots by metal-organic chemical vapor deposition, however much higher intensities (45 W/cm 2 ) were used. 8 Because the surfaces of films produced by MBE are nearly specular ͑typically ϳ1 nm rms roughness over 10 ϫ10 m 2 , according to AFM͒, the light-scattering signal at far from specular angles as used here is many orders of magnitude less than the specular beam. Thus special care was taken to reduce the amount of stray light which entered the detector, for example by scattering of the specular beam from the chamber walls.…”

Local Laser Annealing of Contacts Between MWCNTs and Metallic Electrodes

“…On the other hand, for local processing of various nanostructures, including carbon nanotubes, laser treatment has been successfully used [13][14][15][16][17]. Experiments regarding nanotubes exposure to laser radiation have shown that the high incident laser power density (PD) may cause damages and, consequently, destruction of nanotubes walls.…”