Investigations on the low voltage cathodoluminescence stability and surface chemical behaviour using Auger and X-ray photoelectron spectroscopy on LiSrBO 3:Sm 3+ phosphor

Abstract

Orange-red emissive LiSrBO 3:Sm 3+ phosphors were synthesized through the solid-state reaction method. Under UV radiation (221 nm) and low-voltage electron beam (2 keV, 12 mA/cm 2) excitation, the Sm 3+ doped LiSrBO 3 phosphor shows emission corresponding to the characteristic 4G 5/2- 6H 7/2 transitions of Sm 3+ with the strongest emission at 601 nm. A high stability of cathodoluminescence (CL) emission during prolong electron bombardment with low-energy electrons was observed. Surface sensitive diagnostic tools such as Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) were used to study the surface chemistry. AES results revealed modifications in the surface concentrations of Li, Sr, B, O and C on the surface of the LiSrBO 3:Sm 3+ phosphor as indicated by the changes in their Auger peak to peak heights (APPH) as a function of electron dose. Observed changes in the high resolution XPS spectra of the LiSrBO 3:Sm 3+ surface irradiated with the low energy electron beam provide evidence of compositional and structural changes as a result of the electron beam stimulated surface chemical reactions (ESSCRs). Additional SrO 2 was identified by XPS on the phosphor surface after it received an electron dose of 300 C/cm 2 together with the increase in the concentrations of chemical species containing the B–C–O bonding. The new surface chemical species formed during electron beam bombardment are possibly responsible for the stability of the CL in the LiSrBO 3:Sm 3+ phosphor.