Thin films of SrCuO2 with a tetragonal structure have been synthesized by molecular beam epitaxy. Two different patterns have been observed by reflection high-energy electron diffraction (RHEED) during the alternating supply of strontium and copper under the flow of NO2. Incommensurate streaks appear during the copper supply. The intensity of the incommensurate streak decreases to zero with the strontium supply. We demonstrate that an exact control of the elemental composition of Sr and Cu can be carried out using in-situ intensity monitoring of the incommensurate streak.
