We have investigated the mechanism of degradation of the low voltage cathodoluminescence (CL) efficiency of SrTiO3:Pr,Al,Ga phosphors. Based on Auger electron spectroscopy and x-ray photoelectron spectroscopy study, it is understood that prolonged irradiation of the phosphor with an electron beam of low voltage and high current density causes characteristic changes [(1) accumulation of overlying carbon and (2) reduction of oxygen] to occur on the phosphor surface. These changes are responsible for the rapid degradation of low voltage CL of SrTiO3:Pr,Al,Ga phosphors. The two aforementioned changes are shown to impact CL output in an important way. An accurate accounting of the total impact of the two changes warrants assessment of the importance of other degradation mechanisms. These other degradation mechanisms include both carbon- and noncarbon-related enhanced nonradiative electron-hole recombination at surfaces. (C) 2003 American Vacuum Society.