We demonstrate large-scale (1 kb) high-density crossbar arrays using a Si-based memristive system. A two-terminal hysteretic resistive switch (memristive device) is formed at each crosspoint of the array and can be addressed with high yield and ON/OFF ratio. The crossbar array can be implemented as either a resistive random-access-memory (RRAM) or a write-once type memory depending on the device configuration. The demonstration of large-scale crossbar arrays with excellent reproducibility and reliability also facilitates further studies on hybrid nano/CMOS systems.