A method for depositing a layer on a semiconductor wafer using chemical vapor deposition (CVD). The method includes providing a chamber having an inlet opening and an outlet opening and a channel joining the inlet opening and the outlet opening, wherein the channel is bounded at the bottom by a plane and at the top by a window transmissive to thermal radiation. A semiconductor wafer is disposed so that a surface of the semiconductor lies in the plane, wherein the window has a center region disposed over the semiconductor wafer and an edge region surrounding the center region and not disposed over the semiconductor wafer. A distance between the plane and the window varies across the chamber, the distance being greater at the edge region than at the center region. A tangent applied to a radial profile of the distance at a boundary between the center region and the edge region forms an angle with the plane of not less than 15° and not more than 25°. A deposition gas is conducted through the channel from the gas inlet opening over the semiconductor wafer to the gas outlet opening, wherein a speed at which the deposition gas is conducted varies over the semiconductor wafer according to the varying distance between the plane and the window.