Hydrostatic pressure effects on the optical transitions in the free-standing porous silicon film

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Abstract
Optical absorption and photoluminescence spectra in the range 1.2–2.2 eV have been measured in free-standing films of porous Si under hydrostatic pressures up to 6.4 GPa at room temperature. The absorption rises nearly exponentially in the low energy region. Under pressure, the whole spectrum shifts toward lower energies with a pressure coefficient of about −90 meV/GPa. The photoluminescence spectrum also exhibits a redshift of about −40 meV/GPa. These results are interpreted by analogy with the pressure-induced shrinkage of the optical energy gap seen in amorphous chalcogenide semiconductors.ポーラスシリコンの高輝度で幅広い可視域のレーザ・フォトルミネッセンスが光デバイス工学で強い関心を集めており、本研究ではその起因を究明するために、独自の方法で自立薄膜を製作して光吸収とフォトルミネッセンスの静水圧依存性を測定した。得られた結果はアモルファスカルコゲナイド半導体における光学エネルギーギャップの圧力誘起縮小現象と類似した考え方で解釈できた