ZnSe is one of the promising materials in application to blue light emitting diodes because of its wide direct band gap. Many papers on MIS

[1

2]

and

p-n

[3]

structure blue EL devices of ZnSe bulk single crystal have been reported. Recently

low temperature growth techniques such as MOCVD

[4]

MBE

[5]

and VPE

[6

7]

are of particular interest. Usually these undoped ZnSe epilayers are of low resistivity. The conductivity in undoped ZnSe epilayers may originate from native donors

[8

9]

or extrinsic donor impurities

[10

11]

.In this paper

it is reported that the photoluminescence and electrical properties of ZnSe epilayers grown on (100)-GaAs are influenced by the purity of source materials

and suggested that the conductivity in normally undoped VPE ZnSe was attributed to the extrinsic donor impurities which originated in the contamination of the ZnSe source materials rather than in the native donors or Ga outdiffused from the substrate of GaAs when the growth temperature is low (

T

sub

=500℃).