ELECTROLUMINESCENCE OF DY3-OXIDE( AND SM3+ IONS IN POLYCRYSTALLINE SEMICONDUCTING ZINC)

The electroluminescence of Dy3+ and sm(3+) ions inserted in polycrysta lline semiconducting zinc oxide was studied using a rare earth-doped s intered zinc oxide disc sandwiched between two metallic solders. This device, which corresponds to a metal-semiconductor-metal (MSM) structu re, is similar to a varistor and is able to operate under either ac or de mode. The excitation of the trivalent rare earth ions is a consequ ence of a hot electron impact process. The tare earth ions are located near the grain boundaries. Their luminescence acts as a probe and evi dences hot electrons near the grain boundaries where, in accordance wi th the model of varistors, they are produced by thermionic emission.