Dynamic Coupling Effect in Z²-FET and Its Application for Photodetection

Abstract

In this paper, the application of the zero subthreshold swing and zero impact ionization FET (Z 2 -FET) for photodetection is studied with TCAD simulation. Dynamic coupling effect is utilized to form carrier injection barriers in the partially depleted silicon-on-insulator (PD-SOI) film. Photoelectron accumulation at the front gate interface lowers the hole injection barrier and modulates the turn-on voltage. The light-triggering threshold of the device can be tuned by the front gate voltage, which controls the injection barrier height. We explore two operation modes suited to different applications, and demonstrate the operation of a one-transistor active pixel sensor array. Unlike other image sensors that utilize only one type of carrier, the Z 2 -FET photodetector uses photo-generated holes to induce high electron currents through internal amplification, leading to a high sensitivity of up to 1.8 × 10 5 e-/(lux•s).INDEX TERMS Z 2 -FET, dynamic coupling effect, silicon-on-insulator, photodetection.

A Review on the Recent Progress of Silicon‐on‐Insulator‐Based Photodetectors

“…The application of Z 2 -FET was extended to the photodetection via simulation by Jian et al [56][57][58] The ultrathin top silicon layer in fully-depleted silicon-on-insulator (FDSOI) results in weak light absorption efficiency. This is why partially depleted PD-SOI with thicker silicon layer was used for photodetection.…”

A Review of Sharp-Switching Band-Modulation Devices

“…Light is detected by the abrupt switch from low to high anode current. The turn-on voltage under illumination is the sensing parameter [54,55].…”

“…In Figure 22b, a very small variation in charge density (10 11 cm −2 ) leads to a shift of V ON as large as 1 V, showing outstanding detection capability. [54,55]).…”

“…Figure 21. (a) Evolution of the anode current under exposure to continuous light for various gate voltages and V A = 1 V. (b) Turn ON characteristics of the Z 2 -FET for various intensities of light pulse (adapted from[54,55]). …”