The present disclosure, in some embodiments, relates to a resistive random access memory (RRAM) device. The RRAM device includes a lower electrode over a conductive interconnect, and an upper electrode over the lower electrode. A data storage structure is disposed between the lower electrode and the upper electrode. The data storage structure includes a plurality of metal oxide layers having one or more metals from a first group of metals. A concentration of the one or more metals from the first group of metals changes as a distance from the lower electrode increases.