Balanced Performance Enhancements of a‐InGaZnO Thin Film Transistors by Using All‐Amorphous Dielectric Multilayers Sandwiching High‐k CaCu₃Ti₄O₁₂

Abstract

The requirements of low power consumption and fast operation have necessitated the development of thin film transistors (TFTs) with exploration of new dielectric materials. Here, the unprecedented integration of high‐κ dielectric CaCu3Ti4O12 is reported, yielding significant enhancements in the performance of amorphous InGaZnO TFTs. Using a multilayer structured amorphous Al2O3/CaCu3Ti4O12/Al2O3 dielectric configuration, the performance of the transistors is greatly improved as highlighted with high saturation mobility (>10 cm2 Vs−1), high on/off current ratio (3.8 × 107), low threshold voltage (≈0.51 V), and low subthreshold swing (≈0.45 V decade−1). The balanced performance enhancements are attributed to the lower density of interfacial/bulk trap states and sufficient band offsets.

High energy efficiency nanodielectrics with relaxor ferroelectric polymer and antiferroelectric (Pb 0.97 La 0.02 ) (Zr 0.63 Sn 0.3 Ti 0.07 )O 3 ceramics

“…Antiferroelectric PLZST ceramics synthesised by the solid‐state method have a typical perovskite structure as shown in Figure 2(a). The dielectric measurement of the PLZST indicates that it has a high dielectric constant (523 at 100 Hz) yet a low dielectric loss (0.012 at 100 Hz) as shown in Figure 2(b), which is lower than the common high‐ ε r ceramics, such as BaTiO 3 (∼0.05 at 100 Hz), BaSrTiO 3 (∼0.03 at 100 Hz) and CaCu 3 Ti 4 O 12 (∼0.1 at 100 Hz) [11–14, 33]. The most striking thing is that PLZST is an antiferroelectric ceramic with extremely small P r unlike conventional ferroelectric ceramics such as BaTiO 3 as shown in Figure 2(c)–(d), which means utilising antiferroelectric materials as fillers of nanocomposites may simultaneously allow a high energy efficiency.…”

“…However, high-ε r ceramics such as BaTiO 3 and PVDF-based polymer matrix are both ferroelectrics. Ferroelectrics could form polarised ferroelectric domains spontaneously, which lag behind the instantaneous reverse electric field after being polarised by an external electric field and have a large P r value [10][11][12][13][14][15]. Therefore, PVDF-based polymer/ceramics ferroelectric composites usually have a large P r and will produce a large energy loss during charge-discharge cycles.…”

Balanced Performance Improvement of a-InGaZnO Thin-Film Transistors Using ALD-Derived Al2O3-Passivated High-k HfGdOx Dielectrics

“…The lower capacitance density for Al 2 O 3 contributes to the smaller carrier concentration in the capacitance-coupled channel layer and lower on-state current, restricting the wide application of Al 2 O 3 in TFTs. 5 In addition, carrier mobility is an important parameter that affects the on-state current. Based on Figure 6b, it can be seen that AH has the largest carrier mobility, followed by AHA, while H and HA have the smallest and the penultimate carrier mobility, respectively.…”

“…16 Meanwhile, some other high-k dielectrics with large k values are often accompanied by significant dipole steering polarization, which inevitably leads to dielectric loss 1 and frequency-dependent dielectric constants. 5 To overcome the shortcomings of single high-k gate dielectrics, a laminated structure was designed. The reported lamination designs include inorganic/inorganic structures, such as HfGdO/ HfTiO, 17 2121 and organic/inorganic composite laminates, such as HfO X /PAE/ HfO X , SiO X /Stb/SiO X , and ZrO/PAE/ZrO.…”

“…Due to the high mobility, high optical transparency, and superior large area uniformity, , amorphous indium gallium zinc oxide thin film (α-IGZO) has been regarded as a competitive channel material for oxide-based TFTs. − The driving circuits based on α-IGZO TFTs have demonstrated some satisfactory performance and have been applied in some commercial fields. , Unfortunately, most α-IGZO TFTs based on traditional SiO 2 gate dielectrics work at high operating voltage and high power consumption is required, which seriously limit the application of α-IGZO TFTs in battery-powered portable and wearable electronic devices. Since high-k dielectrics can positively affect the capacitive coupling with the channel layer, and thus correspondingly increase the driving current and lower the operating voltage, considerable efforts have been made to realize highly competitive α-IGZO TFTs using a variety of high-k dielectric materials. − In spite of the promising large dielectric constant, the existing shortcomings for high-k gate dielectrics cannot be ignored.…”