A Kinetic Model for the Generation and Annihilation of Thermally Induced Carrier Donors in a Semiconducting Metal‐Oxide Thin Film

Abstract

Based on a kinetic model involving oxidant diffusion and an oxidation‐reduction reaction, a 3‐parameter equation is derived relating the change in the concentration of thermally induced carrier donors in common metal‐oxide semiconductors (such as indium–gallium–zinc oxide and indium–tin–zinc oxide) to heat‐treatment time. The change in the concentration of such donors is characterized by measuring the shift in the turn‐on voltage of a thin‐film transistor subjected to heat treatments in different atmospheres for different durations. The model parameters are extracted using optimal curve‐fitting techniques, leading to the determination of relevant activation energies from the temperature dependence of the extracted parameters. The proposed model is found to be applicable to metal‐oxide semiconductors of different compositions. It is discovered that the generation of donors in a non‐oxidizing atmosphere is largely suppressed at a temperature below 250 °C, but the effective annihilation of the donors spans over a wider temperature range in an oxidizing atmosphere.

An Integrated Analog Front‐End System on Flexible Substrate for the Acquisition of Bio‐Potential Signals

“…The schematic cross‐sections of an elevated‐metal metal‐oxide (EMMO) IGZO TFT [ 30,31 ] and C's fabricated on flexible polyimide (PI) substrate are exhibited in Figure a,b. For the EMMO TFT with thermally induced source/drain (S/D) regions, the channel length ( L ) is determined by the separation between the S/D electrodes.…”

P‐1: A Study on the Mechanism of Fluorination Enhanced Thermal Stability of IGZO Thin‐Film Transistors Based on a Kinetic Model of Donor‐Defects

“…The respective channel width 𝑊 and length 𝐿 of the TFTs were 50 and 10 m. These TFTs were "initialized" [7] to obtain a consistent 𝑉 | before each series of heat-treatments in different atmospheres. 𝑉 in this work is defined as the gate voltage 𝑉 required to induce a 𝑊normalized drain current 𝐼 of 1 pA/μm at a drain voltage 𝑉 = 5 V.…”

“…The initialization procedure for the series of heat-treatments in an inert N2 atmosphere started with oxidization of the TFTs at 400 °C until 𝑉 saturated at ~0 V. This was followed by a heattreatment in N2 at 300 °C for 2 hrs to drive away any residual oxidant in the oxide layers while keeping a low rate of generation of donor-defects, thus preventing any appreciable shift in 𝑉 [7]. The TFTs were ready for heat-treatment in N2 and the extraction of 𝐾 using Eq.…”

“…This indicates ∆𝑉 changes linearly with 𝑡 at a rate of −𝐾 . For a TFT heat-treated in an oxidizing atmosphere at a sufficiently low temperature 𝑇 < 250 O C when the generation of donor-defects becomes negligible [7], Eq. ( 2) can be approximated as…”

“…Recently reported was a model describing the kinetics of oxidant diffusion and an oxidation-reduction reaction involving the donor-defects in IGZO [7]. The properties of the donordefects can be revealed by analyzing the extracted model parameters and their corresponding activation energy (𝐸 ) values, thus shedding light on the mechanism responsible for the improved thermal stability of IGZO:F TFTs against thermal stress in an inert atmosphere.…”