High energy electron bombardment produces high resistivity layers in n-type GaAsP. The resistivity of the specimen varied from

-cm to

-cm by the irradiation of

electrons./ cm
2at 7MeV. The light-emitting diodes (LED\´s) irradiated in this condition did not exhibit the any optical radiation. It will be shown that this new technique is useful for isolating GaAsP junction devices.