纳米硅粒子的表面氧化及其光致发光特性

Surface Oxidation and Photoluminescence Properties of Silicon Nanoparticle

采用射频等离子体增强化学气相沉积技术制备了纳米晶硅粒子,并对其溶液发光的稳态和瞬态特性进行了研究。稳态光致发光结果显示,新制备的纳米硅粉体表现为峰值位于440 nm附近的蓝色发光,经长时间氧化后,该波段发光强度显著增强,并且出现另一峰值位于750 nm附近的红色发光带。不同波长激发和时间分辨光致发光谱的分析表明,纳米硅粒子蓝色发光归因于粒子内部载流子的带-带跃迁过程,衰减时间在纳秒量级,氧化造成该波段发光衰减时间常数增加。氧化后出现的红色发光来源于载流子经由表面缺陷态的辐射复合,该发光衰减寿命微秒量级。

The silicon nanoparticle have been grown by radio-frequency plasmas-enhanced chemical vapor deposition technique and the photoluminescence（PL）of the silicon suspension have been studied by both steady-state and time-resolved photoluminescence spectra.The steady-state PL spectra of the silicon suspension show that a blue PL band around 440 nm is found for the as-prepared silicon suspension emits.An increase of the intensity for the blue band around 440 nm followed by a red photoluminescence centered at 750 nm after storing the suspension for two months.The steady-state PL spectra excited by different wavelength and time-resolved PL spectra of the samples demonstrate that the blue PL band with a delaytime of nanosecond order is caused by the band-to-band recombination in Si nanocrystals.The oxidation of the silicon nanoparticle causes the decaytime increasing.The red PL band originates from radiation recombination of carries via defect/surface-related states and the delay-time of which is on the order of microsecond.