Characterization of Electroluminescence from One-Dimensionally Self-Aligned Si-Based Quantum Dots

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We have demonstrated self-assembling formation of one-dimensionally self-aligned Si-based quantum dots (QDs) structures and applied them to an active layer of light emitting diodes (LEDs) with a semitransparent Au gate. Under forward bias conditions over threshold biases as low as {\sim}1.2 and {\sim}{-}2.0 V for LEDs formed on n- and p-Si(100), respectively, stable electroluminescence (EL) was observable in the near-infrared region at room temperature. The observed EL spectra could be deconvoluted into mainly two component peaks at {\sim}1140 and {\sim}1100 nm that originated from lower and upper dots, respectively, where both spectrum intensities showed a power-law relationship of the EL intensity with applied bias and input power. Notice that the slope of the component peak for the lower dots was larger than that for the upper dots, indicating that holes were stably stored in the lower dots due to a deep potential well. In fact, when an AC bias as low as {\sim}6.4 V (DC at 2.0 V) was applied to the LEDs with an Au gate formed on the n-Si(100), a single component peak for the lower dots was detected, indicating electron--hole recombination in the lower dots caused by alternate carrier injection from the Si(100) substrate.
2013-04-25