Analysis of the activation energy of the subthreshold current in laser- and solid-phase-crystallized polycrystalline silicon thin-film transistors

Abstract

International audienceAnalysis of the thermal and gate-voltage dependences of the current in the subthreshold region is performed on both low-temperature laser-crystallized and solid-phase-crystallized polycrystallinesilicon (polysilicon) thin-film transistors(TFTs).Temperature measurements are made at first in order to extract the variations of the activation energyEA of the drain current with the gate voltage. The plot of the subthreshold current versus the measuredactivation energy leads to an apparent activation energyEA/n, where the n factor is extracted from the slope of this plot. The n factor is close to 1 for laser-crystallized polysilicon TFTs while it is rather close to 2 for solid-phase-crystallized ones. These two values can be attributed to a different defect distribution in the two differently crystallized TFTs polysilicon active layers

The Influence of Hafnium Doping on Density of States in Zinc Oxide Thin-Film Transistors Deposited via Atomic Layer Deposition

“…In the sub-threshold region, the current of the TFT devices was well described by the Arrhenius thermal activation model [32, 33]:where I D0 is the prefactor, E a is the activation energy, k is the Boltzmann constant, and T is the temperature. E a can be easily extracted by plotting log ( I DS ) and 1/k T (not shown here).…”

A temperature study of photosensitivity in SLS polycrystalline silicon TFTs

“…Regarding the temperature dependence these currents have been found to be thermally activated and described by an expression of the form [20] …”

“…At this point it must be pointed out that this activation energy is expected to be different from the one obtained from the leakage current due to the different nature of the corresponding mechanisms. Regarding the transport parameter n, according to [20] the index value varies between the values 1 and 2. Index value n = 1 corresponds to scattering at grain boundaries while the index value n = 2 to intra-grain defects.…”

Growth of IZO/IGZO dual-active-layer for low-voltage-drive and high-mobility thin film transistors based on an ALD grown Al2O3 gate insulator

“…The negative V TH shift with increasing temperature can be explained by a thermal activation process of the subthreshold drain current. The subthreshold current in amorphous ZnObased multicomponent oxide TFTs was well described by the thermally activated Arrhenius model [12][13][14][15][16], where it was assumed that thermally activated electrons from deep level trap sites into the conduction band move quickly toward the drain electrode due to a lateral electrical field. Therefore, the rate limiting process would be thermal excitation of the trapped charge, and the drain current around the subthreshold current region can be described by the following equation:…”