An apparatus and method for controlling stray radiation within a CVD chamber. A heater array disposed beneath a wafer carrier for radiatively heating of the wafer carrier includes a peripheral or outermost heating element or elements. Scattered radiation originating from a designated segment of the peripheral heating element(s) can be reduced locally by one of several mechanisms, including reducing the emission (e.g., operating temperature) of the designated segment, or capturing or deflecting a portion of the radiation originating from the designated segment. In one embodiment, an electrical connector on a resistance heating element provides the reduced emission from the designated segment. It has been found that radiation thermometers fixed proximate an axis that extends from the center of the wafer carrier and across the designated segment is subject to less stray radiation, thus providing a more reliable temperature reading in the optical wavelengths.