We present a new electro-chemical method for incorporating high concentration Er ions deep into porous silicon layers and its intense photoluminescence at ∼1.54 μm at room temperature. Porous silicon layers prepared by anodic etching of p-type silicon substrates in HF/H2O are immersed in ErCl3/ethanol solution. Then the negative bias relative to a counter platinum electrode is applied to the samples. Er3+ ions are drawn into fine pores of the porous silicon layers by the electric field. After thermal annealing at ∼1300 °C in an O2/Ar atmosphere, the samples show sharp and intense Er3+-related photoluminescence at ∼1.54 μm at room temperature upon excitation with an Ar ion laser.
Effects of hydrogen plasma treatment on the 1.54 μm luminescence of erbium-doped porous silicon Mechanism of the visible electroluminescence from metal/porous silicon/ n -Si devices
Yb3+-related photoluminescence is observed at room temperature from Yb-doped porous silicon layers prepared by the electro-chemical method developed by our group for Er doping of porous silicon layers. After rapid thermal annealing in a pure argon atmosphere at high temperatures (above ∼ 900 °C), samples show a sharp photoluminescence band at around 1.0 μm which is assigned to the intrashell 4f-4f transitions 2F5/2 → 2F7/2 of Yb3+. The enlarged energy bandgap of silicon as a result of anodization makes possible the excitation of Yb3+ 4f-electrons with the recombination energy of photocarriers generated in the host porous silicon layers.
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