Annihilation of arsenic-nitrogen bonding defects in annealed InAs1−xNx quantum dots grown through nitrogen background pressure–controlled SS-MBE

Abstract

We report the self-assembled growth of InAs1−xNx/GaAs quantum dots (QDs) through solid-source molecular beam epitaxy on GaAs (001) substrates. High-resolution X-ray diffraction confirmed that a low nitrogen background pressure of 4 × 10−6 Torr facilitates 2.2% incorporation of nitrogen into the InAs1−xNx QDs, whereas a relatively high pressure of 5 × 10−6 Torr facilitates a low nitrogen incorporation of 0.6%. 19 K photoluminescence (PL) measurements exhibited wide and multi-peaked spreading in nitride QDs, which can be conflicted with nucleation at dislocations caused by nitrogen. As-grown InAs0.978N0.022 QDs exhibited maximum red-shift upto 1358 nm but with a considerably reduced PL intensity, attributed to nitrogen incorporation and As–N defects generated in nitride QD, respectively. The Raman spectra of the InAs0.978N0.022 QDs exhibited a high intensity and evidently reduced full width at half maximum of the In-N like local vibrational mode as compared to the InAs0.994N0.006 QDs, attributed to less number of defects formed during growth. Rapid thermal annealing was conducted in nitrogen atmosphere for 30 s, and a continuous blue-shift was observed upto 800 °C because of the In/Ga interchange and As/N diffusion. For InAs0.978N0.022 QDs annealed at 750 °C, 440-fold higher improvement in PL intensity was realized because of the annihilation of the arsenic-nitrogen (As–N) bonding defects, whereas the InAs/GaAs QDs used as the reference sample exhibited negligible enhancement. The proposed method eases high nitrogen incorporation into InAs QDs, and the annealed nitride QDs have highly favorable optical properties. These experimental results offer insights into the performance of InAs1−xNx-based lasers.