Infrared photo‐induced absorption spectroscopy of porous silicon

摘要: The quantum confinement model, which assigns some of the luminescence features in porous silicon to size quantization Si nano-crystallites, also predicts both conduction and valence bands into sub-levels. In order resolve this effect we have used a new experimental technique called photo-induced infrared absorption spectroscopy. Here, pump, visible laser, optically induces carriers conduction/valence band. Optical transitions between quantized sub-levels are resolved by probe, beam energy range 50-300 meV. A broad signal has been observed 60-250 meV spectral range, agreement with prediction model. However, decreases decreasing temperature, resolving activation about 10 This behavior can be understood if allowed optical from exciton singlet state only. Also, found additional spectrum that correlated Si=O vibrational modes. Out results indicate strong coupling bulk excitonic states surface small nano-crystallites.