ZnS-based ultraviolet (UV) light-emitting diodes with M pi S (metal - a partially compensated high-resistivity p-type layer -n(+)-semiconductor) structure have been fabricated on (1 0 0) n(+)-GaAs substrates by low-pressure metalorganic chemical vapor deposition. The temperature dependence of the peak position and the intensity of the UV electroluminescence (EL) line have been investigated in detail. We have found that the EL properties are qualitatively in good agreement with photoluminescence properties. The UV EL was observed at about 340 nm at room temperature under the reverse bias condition. The EL mechanism is attributed to impact ionization of accelerated electrons in a high-electric field.