Dadlani, A., Acharya, S., Trejo, O., Nordlund, D., Peron, M., Razavi, J., Berto, F., Prinz, F. B., Torgersen, J., "Revealing the Bonding Environment of Zn in ALD Zn(O,S) Buffer Layers through X-ray Absorption Spectroscopy," ACS APPLIED MATERIALS & INTERFACES Vol. 9, Issue 45, pp. 39105-39109, NOV 15 2017.
Zn(O,S) buffer layer electronic configuration is determined by its composition and thickness, tunable through atomic layer deposition. The Zn K and L-edges in the X-ray absorption near edge structure verify ionicity and covalency changes with S content. A high intensity shoulder in the Zn K-edge indicates strong Zn 4s hybridized states and a preferred c-axis orientation. 2–3 nm thick films with low S content show a subdued shoulder showing less contribution from Zn 4s hybridization. A lower energy shift with film thickness suggests a decreasing bandgap. Further, ZnSO4 forms at substrate interfaces, which may be detrimental for device performance.