In general

a single crystal of ZnS

x

Se

1-x

contains native defects which arise from the deviation of stoichiometry in the growth process. These defects have an effect on the electrical and optical properties of single crystals.The purpose of the present investigation is to measure the change of the concentration of Zn vacancy(V

Zn

)in the heat-treated ZnS

x

Se

1-x

wafers using the intensity of I

1

deep

line in the exciton emission spectra.Because I1deep line is known to arise from acceptor of V

Zn

[4]

. For this purpose a wafer specimen was fabricated by cleaving along the (110) plane of the grown ZnS

x

Se

1-x

(x=0.03) single crystal. The wafers were heat-treated in the temperature range of 300-800℃ for 72 hrs.Under the composition (Zn or S/Se or Se) partial pressure and measured by photoluminescence at 4.2 K to observe the bound exciton emission spectra. The exciton emission spectra of the heat-treated ZnS

x

Se

1-x

in Zn pressure and in S/Se pressure at 300℃

500℃

800℃ have been shown in Fig

1-3 (a) and (b)

respectively. The intensity of I

1

deep

line becomes weaker with the increasing temperature of heat-treatment in Zn partial pressure. On the contrary

the intensity of I

1

deep

line becomes stronger in S/Se partial pressure. This result means that the equilibrium between the vapor and the ZnS

x

Se

1-x

. solid during the heat-treatment is controlled by the Se partial pressure and the Zn partial pressure

respectively. Considering the following reaction.Se

2

(g)=Se

Se

+V

Zn

(4)Zn(g)+V

Zn

=Zn

Zn

(5)where Sese and Zn

Zn

are a Se atom and Zn atom occupying a normal Se and Zn site

respectively. Then the concentration of V

Zn

increases with the increasing Se pressure

and decreases with the increasing Zn pressure.Dependence of the intensity ratio on the heat treatment temperature is shown in Fig. 4. It is known from the Fig. 4 that the concentration of V

Zn

is not changed below 300℃

but a change of concentration of V

Zn

is observed above 300℃. Considering that VZn and Cu-doping in ZnSe can separately be controlled

[4]

. Effective control of native defects and doped impurities in compound semiconductors was proposed in this report.