this invention provides methods that permit wafers to be loaded and unloaded in a gas - phase epitaxial growth chamber at high temperatures . specifically , this invention provides a method for moving wafers or substrates that can bathe a substrate being moved in active gases that are optionally temperature controlled . the active gases can act to limit or prevent sublimation or decomposition of the wafer surface , and can be temperature controlled to limit or prevent thermal damage . thereby , previously - necessary temperature ramping of growth chambers can be reduced or eliminated leading to improvement in wafer throughput and system efficiency .