silicon a chamber can be inserted in which the input and output gasses were only hydrogen and for which no rf field was applied such would allow escape time for the gas molecules that were adhered to the surface of the substrate also it would further isolate the gas mixture for the p type silicon from the mixture for the i silicon for deposition of intrinsic silicon any dopant gases that leak from adjacent chambers can be compensated by introducing an equal amount of the opposite dopant gas the concentration of dopant gas is measured then feedback is used to adjust the amount of compensating dopant gas that is added the result is equal effective concentrations of the p type and n type dopants so that the deposited material will be intrinsic silicon rf power may be applied to metal plates located immediately behind each substrate such creates an rf field perpendicular to the surface of the substrates and in the gas mixture that is in the area between the substrates depending on the frequency of the rf and the size of the plates more than one attachment from the rf generator to each plate may be required to avoid non uniformities in the power density of the plasma a multi layer structure with a series of depositions in a single in line system without load.