Negative differential resistance in porous silicon devices at room temperature

• The NDR effect was observed in porous silicon devices at room temperature.
• Resonant tunneling is not responsible for the NDR effect in our case.
• Charge carrier traps are behind the NDR effect in our porous silicon samples.
• We present a simple circuit exploiting the NDR effect for volatile memory devices.

We report a voltage controlled negative differential resistance (NDR) effect at room temperature in two types of devices based on porous silicon (PS): thermally oxidized porous silicon multilayer with Ag electrodes in a sandwich configuration (Ag/c-Si/PS/Ag) and porous silicon single layer with Al electrodes in a coplanar configuration (Al/PS/Al). The NDR effect was observed in current–voltage characteristics and showed telegraphic noise. The NDR effects showed a strong dependence with temperature and with the surrounding atmospheric air pressure. The NDR occurrence was attributed to the blocking of conduction channels due to carrier trapping phenomena. We also experimentally demonstrate porous silicon devices exploiting the NDR effect, with potential applications as volatile memory devices.

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