Growth and optical characterization of InAsN quantum dots

Abstract

Self-assembled InAsN quantum dots (QDs) have been grown by rf-plasma-assisted molecular beam epitaxy (RF-MBE) on GaAs(001) substrates via a 2-monolayer (ML)-thick InAs wetting layer. The InAsN QDs are typically 30 -70 nm in diameter and 3 -7 nm in height. The dot density was 3.6 × 10 9 -2.3 × 10 10 cm -2 for the fluxes corresponding to the nominal thicknesses of 3.0 -4.0 MLs. As the nominal thickness increases, the dot density increases, while the diameter decreases. The low-temperature (10 K) photoluminescence (PL) of the QD samples shows emission spectra in the wavelength range of 1.2 -1.6 µm apparently caused by the N incorporation (0.8 -2.0%) into the QDs. The QD size distribution causes broad emission spectra.

Complicated effects of nitrogen on the structural and optical properties of InAs(N)/GaAs quantum dots

“…Thus, the coherent QD with higher [N] will form later in a shorter duration and show smaller size. [2,5] The reduced dot size results in an increase of the PL peak energy with increasing [N]. Although the AFM and XRD results support the increasing trend of N incorporation into the QD as [N] increases, the actual N concentration in the coherent QD may be far smaller than [N].…”

“…The trend of reduced size of the smaller coherent dots with increased [N] can be explained by the effect of nitrogen on the growth. Adding N will reduce the probability of nucleation of the smaller dots, due to the rougher growing layer surface and/or reduced strain [2,5] . Thus, the coherent QD with higher [N] will form later in a shorter duration and show smaller size.…”

MOVPE growth and photoluminescence properties of InAsN QDs

“…It is expected that the N incorporation into InAs QDs will extend the emission wavelength to 1.3 µm or 1.55 µm for optical fiber communications using QD lasers. A few attempts to grow the InAsN QDs have been done with MOVPE [6,7] and MBE [8]. In this work, the InAsN self-assembled QDs based on the Stranski-Krastanov (S-K) growth mode by MOVPE are studied with focusing on the effect of N incorporation on the QDs formation and photoluminescence (PL) properties.…”

InAsN quantum dots grown on GaAs(001) substrates by MOVPE

“…Thus, the QDs structure could also suppress the B-M effect because of their delta functional form of the DOS even in the case of a rise in residual carrier concentration, and it is expected that the N incorporation into InAs QDs will extend the emission wavelength to the longer region. For this characteristic feature, several attempts to grow the InAsN QDs have been done with metalorganic vapor phase epitaxy (MOVPE) [10] and molecular beam epitaxy (MBE) [11,12]. In this work, the InAs(N) QDs grown by MOVPE have been investigated to elucidate the effect of N incorporation on the structural and photoluminescence (PL) properties.…”