After improving fabrication technic

an observation of Al-A1

2

O

3

-Au light emitting tunneling junctions deposited on underlayers of CaF

2

has been made.The applied bias can be up to 5.3V at room temperature

and the efficiency can be tip to 8.2×10

-4

.The above two datum were respectively higher than before.The emission spectra are characterized by the cutoff frequence near 3.26eV and the peak at around 2.leV.These characteristics can be understood in the results of new experiments accomplished by us andthe present theoretical frame.Particularly

STM has been used to measure the surface roughness. According to our STM topograph of top An-surface of tunnel junction with CaF

2

underlayer and the theory of Labs and Mills

this paper

for the first time

suggests that the above peak around 2.leV perhaps corresponds to surface--plasmonpolariton(SPP)decoupling most efficiently.