In recent years

the research on Ⅱ-Ⅵ compound semiconductors such as ZnSe and CdS has special attention. The most interesting work is to study the free exciton emission in the Ⅱ-Ⅵ crystals under high excitation density

[1]

. Saito et al

[2]

. observed E and P bands in ZnSe in photoluminescence (PL) within 4.2-65K

which they attributed to exciton-electron(E

x

-e)and exciton-exciton (E

x

-E

x

) interaction

respectively. Colak et al

[3]

. reported the stimulated emission in ZnSe crystal excited by electron beam. L. Ma et al. observed the P band excited by N

2

Laser in VPE ZnSe epilayer at 64K. Up to now

there has been no report on E

x

-E

x

interaction in VPE ZnSe epilayer under high excitation density at 77K.In this work

a new band PA Was found at the low energy side of EA band under high excitation density. The origin of the new PA band was investigated.The ZnSe epilayer used in this work was grown on (100) GaAs substrate with VPE method. The ZnSe epilayer was excited by N2 Laser with the pulse width of 10ns

repetition frequency of 10Hz and the maximal pulse density of 2MW/cm2. PL spectra were measured using a grating spectrograph of model 44W with C31034 cooled photomultiplier.Fig.1 and Fig.2 show the PL spectra of the selected (specimen A) and ordinary (specimen B) ZnSe single crystal epilayers under different excitation . densities at 77K.