Method for the deposition of silicon germanium layers

A vertical chemical vapor deposition (CVD) apparatus and methods for the deposition of compound films, such as silicon germanium films, are provided. In a preferred embodiment, the apparatus comprises a process chamber, wherein the process chamber is elongated in a first generally vertical direction; a boat to support a plurality of wafers, wherein individual wafers comprising the plurality of wafers are oriented substantially horizontally, stacked substantially vertically and spaced apart vertically; and a gas injector inside the process chamber, wherein the gas injector extends in a second generally vertical direction over about the height of the boat and comprises a plurality of gas injection holes, wherein the plurality of gas injection holes extends over about the height of the gas injector, and wherein the gas injector has a feed end connected to a source of a silicon-containing gas and a source of a germanium-containing gas. The aggregate cross-section of the holes is relatively large to prevent reactions inside the gas injector and the horizontal cross-section of gas conduction channels inside the gas injector is relatively large to facilitate distribution of the precursor source gases over the height of the boat.