Effect of the chemical composition at the memory behavior of Al/BST/SiO2/Si-gate-FET structure

Abstract

The effect of the chemical composition of the ferroelectric barium strontium titanate (BST) on the memory window behavior of Al/BST/SiO 2 /Si-gate-field effect transistor structure has been investigated. Nanocrystalline Ba x Sr 1-x TiO 3 thin films with different x values have been fabricated as metal-ferroelectric-insulator-semiconductor (MFIS) and metal-ferroelectric-metal (MFM) configurations using a sol-gel technique. The variation of the dielectric constant (e) and tan d with frequency for MFM samples have been studied to ensure the dielectric quality of the material. At low frequencies, e increases as the strontium content decreases, whereas at high frequencies, it shows the opposite variation, which is attributed to the dipole dynamics. The ferroelectricity of the BST within MFM structure has been investigated using C-V characteristics, which show that the ferroelectric hysteresis strength increases as the strontium content decreases. The ferroelectric memory behavior of the MFIS samples has been investigated using C-V characteristics. The results show that the memory window width increases as the strontium content decreases; this is attributed to the grain size and dipole dynamics effect.

Current Progress towards the Integration of Thermocouple and Chipless RFID Technologies and the Sensing of a Dynamic Stimulus

“…Doping can greatly enhance certain properties of the resulting material including loss tangent [36,37], sensitivity [36], and dielectric dispersion [36]. With regard to operating temperatures of this material, works such as that by Nadaud et al in [33] have shown that deposited BST can exhibit permittivity changes as low as 2% between −75 • C and 100 • C. Furthermore, this work also demonstrates varactor operation at temperatures up to 200 • C. Further efforts are needed in characterizing the performance above this level, however this material can and has been deposited in-situ [31,36,38].…”

“…Upon the application of an electric field, the permittivity of this material is reduced in the opposite plane, and this dependence has been modelled and characterized in numerous works including that by Wexler et al in [ 29 ] and by Wang in [ 30 ]. This material has already been used in a host of applications, including its use as a suitable FRAM material [ 31 ]. The hysteretic behavior governing the materials use in FRAM technology is temperature dependent and only occurs in the ferroelectric phase of the material.…”

“…Furthermore, this work also demonstrates varactor operation at temperatures up to 200 °C. Further efforts are needed in characterizing the performance above this level, however this material can and has been deposited in-situ [ 31 , 36 , 38 ].…”

Impact of Annealing Temperature on Electrical Properties of Sol-gel Ba0.90Gd0.10TiO3 Thin Films

“…It is also noted that the C-V curve is asymmetry around the voltage. Saif et al [21] and Masruroh & Toda [22] reported that this shift could be originated from existing an accumulated charge at the film/electrode interface, and could be also due to the variation of work function for the bottom and top electrodes. Furthermore, two maxima peaks for the CV curve forming a butterfly shape is observed, that are attributed to polarization switching as a response to the sweeping voltage for both forward and reversed bias.…”

Characterization and Performance Analysis of BST-Based Ferroelectric Varactors in the Millimeter-Wave Domain

“…Different ferroelectrics were investigated in the literature [12][13][14] but barium and strontium titanate, Ba x Sr 1−x TiO 3 (BST) remains one of the most studied compounds since, among others ferroelectrics, it presents low dielectric losses and one of the largest permittivity variation under applied direct current (dc) bias. The intrinsic dielectric characteristics of the BST material (the Curie temperature defining the particular ferroelectric or paraelectric state of the material at a given temperature, the material losses, the amplitude of permittivity variation under a given bias field) are related to its composition (i.e., the Ba/Sr ratio) and geometry [15,16].…”