Traps contribution on detection time of single electron photodetector (Photo-SET)

In this paper we report charge trapping effect in a few number of nanocrystals silicon (2–4 nc-Si) embedded in SiO₂ layer tunnel oxide of small area single electron photodetector (Photo-SET or nanopixel). The device detection time which estimated using capacitance versus time (C–t) measurements gives us a detection time about 350 s at T = 280 K. Capacitance versus voltage (C–V–T) measurements as a function of temperature confirm the presence of thermally activated trap centers localized at the tunnel oxide layer (trap activation energy: Ea ∼ 0.41 eV and capture section: σ ∼ 1.72 × 10⁻¹⁷ cm²). It is found that traps contribute to determine the detection process state where a threshold voltage shift of 60 mV at T = 280 K which corresponds to the trapping of one electron in the nc-Si dot. This process is probably due to the dominance of tunneling of electrons from traps level to the poly-Si/SiO _x = 1.5 interface via the nc-Si. The Photo-SET estimated detection time is influenced by oxide traps. (papers)