Achieving high-performance multilayer MoSe₂ photodetectors by defect engineering

Optoelectronic properties of MoSe₂ are modulated by controlled annealing in air. Characterizations by Raman spectroscopy and XPS demonstrate the introduction of oxygen defects. Considerable increase in electron and hole mobilities reveals the highly improved electron and hole transport. Furthermore, the photocurrent is enhanced by nearly four orders of magnitudes under 7 nW laser exposure after annealing. The remarkable enhancement in the photoresponse is attributed to an increase in hole trapping centers and a reduction in resistance. Furthermore, the annealed photodetector shows a fast time response on the order of 10 ms and responsivity of 3×10⁴ A/W.