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

Abstract

In this paper we report charge trapping effect in a few number of nanocrystals silicon (2-4 nc-Si) embedded in SiO 2 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 cm 2 ). 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.

Effects of substrate voltage on noise characteristics and hole lifetime in SOI metal-oxide-semiconductor field-effect transistor photon detector

“…In case of QDFET, the hole lifetime in InAs QDs is longer than a hundred seconds, and a reset gate pulse is necessary for refilling the dots with electrons after illumination [3,4]. In the photo-SET, electron lifetime in the nc-Si dots (detection time) can be as long as 350 s at a specific temperature with the contribution of Si/oxide traps [6]. In the present SOI MOSFET, hole lifetime is much shorter probably due to the bulk defects in the SOI layer as estimated in the previous section, the presence of channel electrons in a short distance, and the lose confinement of holes in the shallow potential well created by the pn junction and gate electric field.…”

“…The short lifetime is beneficial in that the device does not require reset operation, but there might be some difficulty in controlling the lifetime to an appropriate value. The contribution of the Si/oxide interface traps [6] to the hole lifetime seems to be small considering the fact that the lifetime becomes longer for higher transverse electric field that makes the hole distribution closer to the interface.…”

“…A type of single-photon detector, which directly counts photo-generated and stored (or trapped) single charges by a sensitive electrometer, is drawing attention because of its potential as a photon-number-resolving detector [1][2][3][4][5][6][7][8]. Quantum dot field-effect transistor (QDFET) [2][3][4] utilizes the GaAs/AlGaAs two-dimensional electron gas (2DEG) channel as an electrometer to detect the photo-generated and trapped holes in the InAs self-organized QDs.…”

“…Quantum dot field-effect transistor (QDFET) [2][3][4] utilizes the GaAs/AlGaAs two-dimensional electron gas (2DEG) channel as an electrometer to detect the photo-generated and trapped holes in the InAs self-organized QDs. Single-electron photodetector (photo-SET) [5,6] with nanocrystal silicon (nc-Si) dots formed by the deposition and annealing of Si-rich oxide utilizes single-electron transistor (SET) as an electrometer to detect photo-generated single charges trapped in the dot or Si/oxide interface. We have also studied the scaled-down silicon-on-insulator (SOI) metaloxide-semiconductor field-effect transistor (MOSFET) [7,8], in which photo-generated holes are stored below the negatively biased gate, and are detected as changes in the bottomchannel electron current.…”