The invention relates to a device for depositing at least one layer on a substrate by means of a process gas which is introduced through a flow channel (4), extending in a vertical direction, of a gas inlet member (3), fixed in place with respect to a reactor housing, into a process chamber (1), extending in a horizontal direction, wherein the process gas leaves a gas outlet opening of a portion of the gas inlet member (3), protruding into the center of the rotationally symmetrical process chamber (1), and flows in a radially outward direction via a base (8′) of the process chamber (1), extending in a horizontal direction and rotating about the center, on which base the substrate lies. In order to improve the gas flow directly above the base of the process chamber, it is proposed that the front (3′) of the gas inlet member (3) protrudes into a pot-like recess (23) and an end portion (6′) of a gas deflecting face (6) is flush with the base (8′).