Observation of deep electron states in n-type Al-doped ZnS/sub 1-x/Te/sub x/ grown by molecular beam epitaxy

The deep level transient spectroscopy (DLTS) technique was used to investigate deep electron states in n-type Al-doped ZnS/sub 1-x/Te/sub x/ epilayers grown by molecular beam epitaxy (MBE). Deep level transient Fourier spectroscopy (DLTFS) spectra of the Al-doped ZnS/sub 1-x/Te/sub x/ (x = 0, 0.017, 0.04 and 0.046, respectively) epilayers reveal that Al doping leads to the formation of two electron traps at 0.21 and 0.39 eV below the conduction band. DLTFS results suggest that in addition to the roles of Te as a component of the alloy as well as isoelectronic centers, Te is also involved in the formation of an electron trap whose energy level relative to the conduction band decreases as Te composition increases.