H⁻ ion implantation induced ten-fold increase of photoluminescence efficiency in single layer InAs/GaAs quantum dots

We demonstrate a ten-fold increase in photoluminescence (PL) efficiency from 50 keV H⁻ ion-implanted InAs/GaAs quantum dots (QDs) at a temperature of 8 K and/or 145 K. Enhancement occurred without post-annealing treatment. PL efficiency increased with increasing implantation fluence from 6×10¹² ions/cm² up to an optimum value of 2.4×10¹³ ions/cm², beyond which PL efficiency decreased drastically (up to a fluence of 2.4×10¹⁵ ions/cm²). Passivation of non-radiative recombination centres (due to direct interaction of H⁻ ions with lattice defects) and de-excitation of photo-generated carriers to QDs through quantum mechanical tunnelling via H⁻ ion-induced defects (e-traps) that are created near the QD–cap layer interface, resulted in PL efficiency enhancement. Shallow e-traps with activation energy ∼90 meV and 30 meV created near the conduction band of GaAs cap layer for the samples implanted with H⁻ of fluence 6×10¹² and 2.4×10¹³ ions/cm² respectively are identified using low temperature PL study. Contribution of de-trapped electrons from the e-traps to the QDs enhanced the PL efficiency at 145 K. Cross-section transmission electron microscopy and X-ray diffraction study revealed that the structural damage created by H⁻ ions at the high fluence level of 2.4×10¹⁵ ions/cm², caused the degradation in PL efficiency. - Highlights: • Self-assembled single layer InAs/GaAs quantum dots. • Low energy hydrogen ion implantation. • PL efficiency enhancement for implanted samples. • Eradication of defects from dots and capping layers