$1.6 \ \mu \mathbf{m}$ Emission from InAs QDs in Metamorphic InGaAs Matrix

Abstract

We discussed the growth of InAs quantum dots (QDs) in metamorphic InGaAs matrix for long-wavelength lasers on GaAs substrates by molecular beam epitaxy (MBE). After a 5-step graded InGaAs metamorphic buffer layer (MBL) firstly grown on GaAs, InAs QDs were embedded in two InGaAs confining layers (CLs) with the same indium composition as the final indium composition in InGaAs MBL. High QD density of $6.5\times 10^{10}\text{cm}^{-2}$ was observed by AFM. $2\theta$ curve clearly indicated peaks from GaAs substrate and graded InGaAs MBL. The final indium composition of about 41% in graded InGaAs MBL was extracted from the peak positions. Two peaks at $1.42 \mu \mathrm{m}$ and $1.6 \mu \mathrm{m}$ were found in Photoluminescence (PL) spectrum at room temperature (RT). Calculated band gap of In 0.41 Ga 0 . 59 As bulk is consistent with the emission wavelength of $1.42 \mu \mathrm{m}$ . The emission wavelength of InAs QDs was extended to $1.6 \mu \mathrm{m}$ due to strain reduction in QDs caused by metamorphic InGaAs matrix with such high indium composition of 41%. The RT emission wavelength of $1.6 \mu \mathrm{m}$ from metamorphic InAs/InGaAs QDs on GaAs refreshes the longest wavelength reported previously.