In this paper

the behaviour of forming process and the electrical and optical properties in direct current electroluminescent(DCEL)ZnS:Mn

Cu powder panels are presented.By using static and dynamic methods to measure the current-voltage(

i

~

V

)characteristic curves of newly-formed panels

it was found that

the curves exhibit a rectifying behaviour and a phase modulation effect(asymmetry in phaseshift)

and the luminescent region is localized in adjacent to the anode.In order to further examine whether a barrier is existed in the formed panel

the anode and cathode surface is illuminated by light respectively.Thereis a photovoltaic effect when the anode is illuminated

but not when the cathode is.By inference from this effect

it seems probable that a CuxS-ZnS barrier would be created near the anode of the formed panel.Increasing the forming voltage or prolonging the forming time

the capacitance of the panel decreases and the luminescent region migrates gradually out from the anode into the phosphor layer.At last

the light transmitted from the cathode surface becomes much more intense than that from the anode surface.This fact of migration of luminescent region would be one of the significant factors which cause the panels to age.To analyse the electrical conduction and excitation mechanisms of the panels a p-v-n junction model is proposed.By using the equivalent circuit and simplifying the calculations

the model is able to explain the results obtained by Alder et al.

i.e.

the asymmetry in the i~V characteristics increases with increasing forming voltage;the reciprocal capacitances are linear with the forming voltages for both forward and backward voltage;the lines with different slopes do not pass through the origin of the 1/c~V diagram.Also investigated was the forming process under sinusoidal

20-20kHz source.For gap type devices

several adjacent luminescent regions exist simultaneously even in a gap

and the luminescent regions are nonuniform in shape.Although there are in practice so many factors that may contribute to the forming and aging processes and thus there is at present no common agreement on the processes

we rather consider that the overheating of the phosphor layer is a most important factor inducing the forming and aging processes.