[en] Centimeter-sized 2D layered α-MoO₃ single crystal has been grown by a facile physical vapor deposition method. The lateral size of α-MoO₃ single crystals can be tunable from micrometer to centimeter by controlling the inner diameter of the quartz tube reaction chamber. The as-grown α-MoO₃ exhibits strong in-plane Raman anisotropy, where A _g Raman modes give the direction of crystallographic orientation, which can be used to rapidly and precisely identify the crystallinity of large-area α-MoO₃ through selected-area angel-resolved polarized Raman spectroscopy. Moreover, the photodetectors based on annealed α-MoO₃ single crystals exhibit excellent optoelectronic performance with a photoresponsivity of 65.6 A W⁻¹ and a fast photoresponse time of 2 s. (paper)