MONITORING OF MOCVD REACTANTS BY UV ABSORPTION

In this paper, we describe how UV absorption measurements can be used to measure the flow rates of metalorganic chemical vapor deposition (MOCVD) reactants. This method utilizes the calculation of UV extinction coefficients by measuring the total pressure and absorbance in the neat reactant system. The development of this quantitative reactant flow rate monitor allows for the direct measurement of the efficiency of a reactant bubbler. We demonstrate bubbler efficiency results for TMGa, and then explain some discrepancies found in the TMA1 system due to the monomer to dimer equilibrium. Also, the UV absorption spectra of metalorganic and hydride MOCVD reactants over the wavelength range 185 to 400 nm are reported.