The aim of this paper is to report the optical properties of K2SiF6:Mn4+ phosphor prepared by wet chemical etching of Si wafers in a HF/KMnO4 mixed solution. The luminescence centers of sharp red emission at similar to 630 nm are ascribed to the Mn4+ ions in the octahedral site of K2SiF6 gained by the activation of local vibration modes ((4)A(2)-> E-2). All the expected electronic and vibronic origins of the E-2 ->(4)A(2), (4)A(2)-> T-4(2), and (4)A(2)-> T-4(1) transitions of the Mn4+ ions are identified and depicted in the Tanabe-Sugano diagram of a 3d(3) transition-metal system. The temperature-dependent photoluminescence properties suggest that the anti-Stokes/Stokes intensity ratio can be explained by the Maxwell-Boltzmann factor but only at low temperatures and low-excitation power intensities. (c) 2008 The Electrochemical Society. [DOI: 10.1149/1.2993159] All rights reserved.