Composition-controlled metal-organic chemical vapor deposition of La 2 CuO 4 thin films using ultraviolet absorption sensors to provide incoming precursor flux control is reported. These sensors provide a more flexible and sensitive alternative to ultrasonic sensors. The films were c-axis oriented and semiconducting as grown on LaAlO 3 substrates. Chemical oxidization at room temperature in a sodium hypobromite solution resulted in an expansion of the c-axis lattice parameter and the conversion of the semiconducting film into a superconductor with a zero-resistance transition temperature of 32 K.