Determination of nonradiative surface layer thickness in quantum dots etched from single quantum well GaAs/AlGaAs

Abstract

Low-temperature cathodoluminescence spectroscopy was used to investigate the luminescence efficiency of reactive ion etched quantum dots, varying in diameter from 200 μm down to 60 nm. The luminescence efficiency was found to be degraded both with decreasing nanostructure size and with increasing etch depth. A solution to the standard model for diffusion and recombination was applied to the data to determine the surface recombination velocity S. We found that for dots smaller than the diffusion length, the standard diffusion model becomes insensitive to the value of S and fails to predict that there is a size of dot in which the luminescence is completely extinguished. To understand qualitatively the luminescence degradation in etched nanostructures we describe a damage layer thickness ξ. The value of ξ determines the smallest quantum structure that will still emit light. We show that ξ increases with increasing etch depth and is therefore dependent on etching conditions.

Recombination dynamics in dry-etched (Cd,Zn)Se/ZnSe nanostructures: Influence of exciton localization

“…In deep etched wires and dots, the reduction of the exciton lifetime and the normalized PL intensity with decreasing size is usually explained by a diffusion of free excitons to the sidewalls followed by a nonradiative recombination process at the surface. [9][10][11][13][14][15][16][17][18] This picture is confirmed by experimental data, e.g., for GaAs/͑Al,Ga͒As wires 14,16 and dots, 18 ZnSe/Zn͑Se,S͒ wires, 17 and CdTe/͑Cd,Zn͒Te wires. 10 However, there are recent reports on ͑Cd,Zn͒Se/ZnSe wire structures, 17,19 where the recombination lifetime observed in time-resolved PL spectroscopy remains approximately constant even if the lateral size is reduced down to 20 nm.…”

Cathodoluminescence study of GaAs quantum wells and of submicron dots fabricated by magnetron reactive ion etching

“…Reduced luminescence efficiency has been reported by several research groups for different etching techniques. [1][2][3][4] However, in these cases, values for the surface recombination velocity ͑S͒ and the diffusion length ͑L͒ were obtained by simultaneous fits to the standard model for carrier drift diffusion, 1 or by using an assumed value for L. In this letter, a study of sidewall damage in arrays of submicron features fabricated by magnetron reactive ion etching ͑MIE͒ is presented. This technique is a particularly promising method for high-reactive flux, low-damage dry etching.…”

Electron cyclotron resonance plasma etching of GaSb-based alloys

“…12 This model, proposed by Clausen et al, was originally applied to a cathodoluminescence study of etched GaAs/AlGaAs quantum-well structures, although it has been used in other photoluminescence studies as well. 15 In steady state, ␦n/␦tϭ0, and the excess minority-carrier FIG.…”