We have proposed and developed an integrated surface multi-junction MOM (metal-oxide-metal). After being treated by a special electro-forming process, light emission from MOM at room temperature has been observed. The I-V characteristic curve of MOM presents a negative resistance feature at low atmospheric pressure., and a memory effect in air. When multi-junction MOM interacts with a laser or a microwave beam, it shows good performances in producing fast responsie signals. The device has the potential application of producing electro-magnetic oscillation in the region from microwave to light.