The characteristics of ACEL in ZnS:Er

3+

thin films grown by ALE method were reported for the first time. Especially

at high Er

3+

concentration

red emission spectral line corresponding to the transition from

4

F

9/2

to

4

I

15/2

was strongly increased. The cross-relaxation process between Er ions was proposed for the interpretation of the experimental results.The EL device is glass-SnO

2

-Y

2

O

3

-ZnS:Er

3+

-Y

2

O

3

-Al sandwich structure.The Y

2

O

3

insulator layer was made by electro-beam evaporation.ZnS:Er

3+

active layer was grown by ALE method. The thicknesses of Y

2

O

3

layer and ZnS:Er

3+

active layer were about 300nm and 400nm

respectively. The concentrations of Er

3+

in ZnS ranging from 0.05% to 12%(wt).