A memory circuit includes a memory array including a plurality of memory cells, each memory cell of the plurality of memory cells including an n-type channel layer including a metal oxide material, and a gate structure overlying and adjacent to the n-type channel layer, the gate structure including a conductive layer overlying a ferroelectric layer. The memory circuit is configured to apply a gate voltage to each memory cell of the plurality of memory cells in first and second write operations, the gate voltage has a positive polarity and a first magnitude in the first write operation and a negative polarity and a second magnitude greater than the first magnitude in the second write operation.