NSF Award
9660463
*** ABSTRACT 9660463 Nelson This Small Business Innovation Research Phase I project will develop a high-speed, in-line gas monitor for control of Gas Mixing in chemical vapor deposition systems. CVD has emerged as an important fabrication technique for advanced semiconducting and optoelectronic thin film materials. Without real-time monitoring and closed-loop control of the growth chemistry, it is extremely difficult to fabricate structures with multi-layered and graded compositional profiles. Fourier transform infrared spectroscopy has been demonstrated for process monitoring and recent innovations have improved the ruggedness and signal-to-noise ratio while reducing the size, weight, and cost of commercial instruments. In many applications, however, a long optical pathlength is required to achieve the desired measurement sensitivity. The use of standard, long-path "White" cells can significantly increase the pathlength while simultaneously increasing the sampled volume. This increased volume can increase the response time from spectral measurement and data analysis time to the time it takes to fill the cell with a representative sample, which can be on the order of several minutes. This Phase I project will develop a fast-response, in-line optical system to be used in conjunction with an advanced FT-IR spectrometer to provide real-time process and quality control in low flow systems such as CVD reactors. In addition to process and quality control in CVD and other chemical reactors, the proposed analysis system will be capable rapid measurement (<1 sec) of other gases such as automobile exhaust, waste-site effluents, and fugitive emissions. The rapid response time will improve the efficacy of FT-IR and other spectroscopic techniques for detecting process upsets, fires, explosive atmospheres, and hazardous workplace conditions. ***
