Structural features, low-temperature luminescence properties of Li-doped SnO2 nanobelts and their transitional temperature

Abstract

Li-doped SnO2 nanobelts have been fabricated by thermal evaporation based on vapor-solid (VS) growth mechanism. The three feature-peaks of Raman scattering spectra at 475 cm −1 (Eg), 634 cm −1 (A1g), and 776 cm −1 (B2g) at room temperature indicate that the samples still keep the rutile structure. One vibration mode at 591 cm−1 is observed from the Li-doped SnO2 nanobelts due to a slight distortion of SnO2. XPS spectra indicate that lithium is incorporated mainly in substitutional sites in the rutile structure of SnO2. The low-temperature (less than 90 K) photoluminescence properties show that there is an intensive broadband blue light emission centered at 480 nm (BL, 2.583 eV). When the temperature is larger than 90 K, the blue light emission peak is quenched and one yellow light emission centered at 580 nm (YL, 2.138 eV) is dominated. The analyses of Gaussian-fitted from 10 to 90 K reveal that the three peaks show different temperature dependences with increasing temperature. The characteristic temperature of quenching is the 90 K served as a transitional temperature. Activation energy of Ea about 40 meV is obtained from the integrated intensity of the YL band using the Arrhenius formula.