Abstract: An apparatus and method are provided for depositing silicon on a substrate in a deposition chamber wherein deposition of impurities can be effectively prevented. Impurities are ionized according to the invention to form impurity ions which are collected so as to prevent their deposition on the substrate.

Abstract: Comparator apparatus and method produce a signal representative of the relationship between two signals. In a further aspect, the comparator apparatus and method are used to provide a calibration and status monitor for a chromatographic analyzer.

Abstract: An optical absorbance detector which can be used in process chromatographic analyzers is provided. Improvements are provided in noise reduction, temperature stability, operator convenience and construction. Noise reducing features include electrical signal filtering and optical system alignment. Temperature stability features include an electronic preamplifier inside the oven and a temperature controller to maintain an integrated circuit at a constant temperature. Operator conveniences include built-in calibration for electronic circuits and easy optical filter replacement. Construction features include explosion resistance and small size.

Abstract: Comparator apparatus and method produce a signal representative of the relationship between two signals. In a further aspect, the comparator apparatus and method are used to provide a calibration and status monitor for a chromatographic analyzer.

Abstract: Long-term stability for an emission type plasma spectrometer is provided by automatically adjusting the output of a power supply which is being utilized to create the plasma. The automatic adjustment is based on a feedback signal which is derived by monitoring an atomic line of a carrier gas.

Abstract: A method and apparatus for adjusting the gain of the sample and reference outputs of a chromatographic analyzer detector with respect to a reference voltage is provided. The detector sample output is compared to a voltage reference and this comparison is utilized to drive a dual color light-emitting diode. The light-emitting diode emits a first color when the gain is too high and emits a second color when the gain is too low. When the gain is correctly set so that the sample output is equal to the reference voltage when only carrier fluid is flowing through the sample side of the chromatographic analyzer detector, the light-emitting diode emits no light, thereby indicating that the gain is correctly set. A corresponding procedure is utilized to set the gain of the reference side of the chromatographic analyzer detector. The light-emitting diodes are also particularly useful as a diagnostic aid in optical absorbence chromatographic analyzer detector systems.