In thin film deposition processes, the deposition temperature is one of the crucial process parameters for obtaining films with desired properties. Usually the optimum deposition temperature is found by conducting several depositions sequentially in a time consuming process. This paper demonstrates a facile and rapid route of the simultaneous thin film deposition at six different deposition temperatures ranging from 100 to 1000 8C. Cuprite (Cu 2 O) was chosen for the study as this material is of interest for energy applications. The thin films are assessed for their crystallographic, microstructural, Raman scattering, and photoelectrochemical properties. The results show that the utilization of a step heater leads to the rapid optimization of thin film microstructures of an absorber material used in photoelectrochemistry. This results in a structure zone diagram for Cu 2 O. For a substrate temperature of 600 8C, an optimum between crystallinity and morphology occurs. 1 Introduction Thin film semiconductors in photoelectrochemical applications need to fulfil numerous properties. Whereas the search for new absorber and catalytic materials by combinatorial and high-throughput methods is currently addressed, the high-throughput optimization of deposition parameters, e.g., deposition temperature, however, is less developed. Finding optimal deposition conditions for even relatively simple metal oxide semiconductors for photoelectrochemical applications [1], usually requires careful evaluation of the different properties of a thin film like morphology, crystal structure, and interface formation [2][3][4][5]. In reactive magnetron sputtering, these properties can be tuned by deposition parameters like applied power, gas flow, substrate rotation, deposition geometry, total or partial gas pressure, and substrate temperature. These parameters are, however, interdependent. Attaining the desired metal oxide phase (e.g., competing phase formation between CuO and Cu 2 O) adds to the overall complexity of the problem of finding optimal deposition parameters [6]. Evaluating all possible optimization