Strongly Confined Bi₂Se₃ Quantum Dots via Pulsed Laser Ablation in Liquids

Bismuth selenide (Bi₂Se₃) is a binary compound displaying a strong spin-orbit coupling, resulting in a narrow bulk bandgap material with a gapless metallic surface. By shrinking the size of Bi₂Se₃ within the strong confinement regime, its optoelectronic properties changed drastically. To achieve this goal, strongly confined Bi₂Se₃ quantum dots (QDs) were produced by pulsed laser ablation in liquids (PLAL). The laser used for the synthesis was a nanosecond Nd/YAG laser emitting at 1064 nm and pulsing at ∼13 mJ/pulse. The irradiation of the bulk target was performed at 1 kHz in acetone and lasted 5 min. Finally, the Bi₂Se₃ QDs were spherical in shape with a diameter around 7 ± 3 nm and displaying an energy bandgap of 1.97 ± 0.19 eV.