Gas recycling in a previously patented silicon epitaxial reactor is described. As far as HCI content is kept under certain limits to avoid Si etching during deposition, simple gas recycling has two main advantages: an important reduction in carrier gas waste, and, in some cases, also an increase in the deposition efficiency. A further step, also discussed here, is to avoid using source gases as such, but to produce them in-situ in a closed loop, by means of etching electronic grade Si in a separate chamber, to deposit it afterwards in the epitaxial chamber. This solution avoids carrier gas waste, which has to be introduced only initially, and gives theoretical efficiencies of 100%, which is a big difference with usual epitaxial reactors nowadays. (c) 2005 Elsevier B.V. All rights reserved.