Editorial

3 pages, 160 KiB

Open AccessEditorial

Applications of Thin Films in Microelectronics

by Hyuk-Jun Kwon

Electronics 2022, 11(6), 931; https://doi.org/10.3390/electronics11060931 - 16 Mar 2022

Cited by 1 | Viewed by 2652

Due to their versatility, thin films, which can be formed through many different approaches, are being used in various applications in microelectronics[...] Full article

(This article belongs to the Special Issue Applications of Thin Films in Microelectronics)

Research

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11 pages, 36185 KiB

Open AccessArticle

Semiconducting Polymer Nanowires with Highly Aligned Molecules for Polymer Field Effect Transistors

by Keon Joo Park, Chae Won Kim, Min Jae Sung, Jiyoul Lee and Young Tea Chun

Electronics 2022, 11(4), 648; https://doi.org/10.3390/electronics11040648 - 18 Feb 2022

Cited by 2 | Viewed by 2014

Abstract

Conjugated polymers have emerged as promising materials for next-generation electronics. However, in spite of having several advantages, such as a low cost, large area processability and flexibility, polymer-based electronics have their own limitations concerning low electrical performance. To achieve high-performance polymer electronic devices, [...] Read more.

Conjugated polymers have emerged as promising materials for next-generation electronics. However, in spite of having several advantages, such as a low cost, large area processability and flexibility, polymer-based electronics have their own limitations concerning low electrical performance. To achieve high-performance polymer electronic devices, various strategies have been suggested, including aligning polymer backbones in the desired orientation. In the present paper, we report a simple patterning technique using a polydimethylsiloxane (PDMS) mold that can fabricate highly aligned nanowires of a diketopyrrolopyrrole (DPP)-based donor–acceptor-type copolymer (poly (diketopyrrolopyrrole-alt-thieno [3,2-b] thiophene), DPP-DTT) for high-performance field effect transistors. The morphology of the patterns was controlled by changing the concentration of the DPP-based copolymer solution (1, 3, 5 mg mL⁻¹). The molecular alignment properties of three different patterns were observed with a polarized optical microscope, polarized UV-vis spectroscopy and an X-ray diffractometer. DPP-DTT nanowires made with 1 mg mL⁻¹ solution are highly aligned and the polymer field-effect transistors based on nanowires exhibit more than a five times higher charge carrier mobility as compared to spin-coated film-based devices. Full article

(This article belongs to the Special Issue Applications of Thin Films in Microelectronics)

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9 pages, 2313 KiB

Open AccessArticle

Ferroelectric Induced UV Light-Responsive Memory Devices with Low Dark Current

by Hanleem Lee and Young Tea Chun

Electronics 2021, 10(16), 1897; https://doi.org/10.3390/electronics10161897 - 07 Aug 2021

Cited by 3 | Viewed by 2254

Abstract

We developed solution-processed hybrid photodetectors with a poly (9-vinylcarbazole)/zinc oxide nanoparticle photoactive layer and a poly (vinylidene fluoride-co-trifluoroethylene) ferroelectric copolymer buffer layer on flexible plastic substrates. The presence of a ferroelectric-poling interface layer significantly enhanced the charge transfer and responsivity of the photodetectors [...] Read more.

We developed solution-processed hybrid photodetectors with a poly (9-vinylcarbazole)/zinc oxide nanoparticle photoactive layer and a poly (vinylidene fluoride-co-trifluoroethylene) ferroelectric copolymer buffer layer on flexible plastic substrates. The presence of a ferroelectric-poling interface layer significantly enhanced the charge transfer and responsivity of the photodetectors under ultraviolet (UV, 365 nm) light exposure. The responsivity of the device reached 250 mA/W at a reverse bias of 5 V and incident light intensity of 27.5 μW/cm². This responsivity was four times higher than that of a device without the ferroelectric copolymer layer (64 mA/W) under the same conditions. The response time of the device to incident UV light also improved from 322 to 34 ms with the addition of the ferroelectric copolymer layer. In addition, the flexible device exhibited a stable performance in an air environment up to a maximum strain of 0.3 under bending stress. Finally, a UV-light-responsive memory device was successfully fabricated by using the developed hybrid photodetector and liquid crystals. This device showed a colour change from white to black upon UV illumination, and the on-state of the device was maintained for 30 s without light exposure owing to the polarization of poly (vinylidene fluoride-co-trifluoroethylene). Full article

(This article belongs to the Special Issue Applications of Thin Films in Microelectronics)

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9 pages, 3019 KiB

Open AccessArticle

Improved Negative Bias Stress Stability of Sol–Gel-Processed Li-Doped SnO₂ Thin-Film Transistors

by Hyeon-Joong Kim, Do-Won Kim, Won-Yong Lee, Sin-Hyung Lee, Jin-Hyuk Bae, In-Man Kang and Jaewon Jang

Electronics 2021, 10(14), 1629; https://doi.org/10.3390/electronics10141629 - 08 Jul 2021

Cited by 7 | Viewed by 2359

Abstract

In this study, sol–gel-processed Li-doped SnO₂-based thin-film transistors (TFTs) were fabricated on SiO₂/p+ Si substrates. The influence of Li dopant (wt%) on the structural, chemical, optical, and electrical characteristics was investigated. By adding 0.5 wt% Li dopant, the oxygen [...] Read more.

In this study, sol–gel-processed Li-doped SnO₂-based thin-film transistors (TFTs) were fabricated on SiO₂/p+ Si substrates. The influence of Li dopant (wt%) on the structural, chemical, optical, and electrical characteristics was investigated. By adding 0.5 wt% Li dopant, the oxygen vacancy formation process was successfully suppressed. Its smaller ionic size and strong bonding strength made it possible for Li to work as an oxygen vacancy suppressor. The fabricated TFTs consisting of 0.5 wt% Li-doped SnO₂ semiconductor films delivered the field-effect mobility in a 2.0 cm²/Vs saturation regime and I_on/I_off value of 1 × 10⁸ and showed enhancement mode operation. The decreased oxygen vacancy inside SnO₂ TFTs with 0.5 wt% Li dopant improved the negative bias stability of TFTs. Full article

(This article belongs to the Special Issue Applications of Thin Films in Microelectronics)

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10 pages, 1914 KiB

Open AccessArticle

Effects of Active Layer Thickness on the Electrical Characteristics and Stability of High-Mobility Amorphous Indium–Gallium–Tin Oxide Thin-Film Transistors

by Dae-Hwan Kim, Hyun-Seok Cha, Hwan-Seok Jeong, Seong-Hyun Hwang and Hyuck-In Kwon

Electronics 2021, 10(11), 1295; https://doi.org/10.3390/electronics10111295 - 28 May 2021

Cited by 16 | Viewed by 3298

Abstract

Herein, we investigated the effects of active layer thickness (t_S) on the electrical characteristics and stability of high-mobility indium–gallium–tin oxide (IGTO) thin-film transistors (TFTs). IGTO TFTs, with t_S values of 7 nm, 15 nm, 25 nm, 35 nm, and [...] Read more.

Herein, we investigated the effects of active layer thickness (t_S) on the electrical characteristics and stability of high-mobility indium–gallium–tin oxide (IGTO) thin-film transistors (TFTs). IGTO TFTs, with t_S values of 7 nm, 15 nm, 25 nm, 35 nm, and 50 nm, were prepared for this analysis. The drain current was only slightly modulated by the gate-to-source voltage, in the case of the IGTO TFT with t_S = 50 nm. Under positive bias stress (PBS), the electrical stability of the IGTO TFTs with a t_S less than 35 nm improved as the t_S increased. However, the negative bias illumination stress (NBIS) stability of these IGTO TFTs deteriorated as the t_S increased. To explain these phenomena, we compared the O1s spectra of IGTO thin films with different t_S values, acquired using X-ray photoelectron spectroscopy. The characterization results revealed that the better PBS stability, and the low NBIS stability, of the IGTO TFTs with thicker active layers were mainly due to a decrease in the number of hydroxyl groups and an increase in the number of oxygen vacancies in the IGTO thin films with an increase in t_S, respectively. Among the IGTO TFTs with different t_S, the IGTO TFT with a 15-nm thick active layer exhibited the best electrical characteristics with a field-effect mobility (µ_FE) of 26.5 cm²/V·s, a subthreshold swing (SS) of 0.16 V/dec, and a threshold voltage (V_TH) of 0.3 V. Moreover, the device exhibited robust stability under PBS (ΔV_TH = 0.9 V) and NBIS (ΔV_TH = −1.87 V). Full article

(This article belongs to the Special Issue Applications of Thin Films in Microelectronics)

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12 pages, 7678 KiB

Open AccessArticle

Influence of Active Channel Layer Thickness on SnO₂ Thin-Film Transistor Performance

by Do Won Kim, Hyeon Joong Kim, Changmin Lee, Kyoungdu Kim, Jin-Hyuk Bae, In-Man Kang and Jaewon Jang

Electronics 2021, 10(2), 200; https://doi.org/10.3390/electronics10020200 - 17 Jan 2021

Cited by 10 | Viewed by 3261

Abstract

Sol-gel processed SnO₂ thin-film transistors (TFTs) were fabricated on SiO₂/p₊ Si substrates. The SnO₂ active channel layer was deposited by the sol-gel spin coating method. Precursor concentration influenced the film thickness and surface roughness. As the concentration of [...] Read more.

Sol-gel processed SnO₂ thin-film transistors (TFTs) were fabricated on SiO₂/p₊ Si substrates. The SnO₂ active channel layer was deposited by the sol-gel spin coating method. Precursor concentration influenced the film thickness and surface roughness. As the concentration of the precursor was increased, the deposited films were thicker and smoother. The device performance was influenced by the thickness and roughness of the SnO₂ active channel layer. Decreased precursor concentration resulted in a fabricated device with lower field-effect mobility, larger subthreshold swing (SS), and increased threshold voltage (V_th), originating from the lower free carrier concentration and increase in trap sites. The fabricated SnO₂ TFTs, with an optimized 0.030 M precursor, had a field-effect mobility of 9.38 cm²/Vs, an SS of 1.99, an I_on/I_off value of ~4.0 × 10⁷, and showed enhancement mode operation and positive V_th, equal to 9.83 V. Full article

(This article belongs to the Special Issue Applications of Thin Films in Microelectronics)

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15 pages, 2258 KiB

Open AccessArticle

Investigation of Structural and Optoelectronic Properties of Organic Semiconductor Film Based on 8-Hydroxyquinoline Zinc

by María Elena Sánchez Vergara, Lorena Ramírez Vargas, Citlalli Rios, Bertha Molina and Roberto Salcedo

Electronics 2021, 10(2), 117; https://doi.org/10.3390/electronics10020117 - 08 Jan 2021

Cited by 6 | Viewed by 2654

Abstract

In this work, we investigated an organic semiconductor based on zinc 8-hydroxyquinoline (ZnQ₂) and tetracyanoquinodimethane (TCNQ), which can be used as a photoactive layer in organic devices. The semiconductor was optimized by applying density-functional theory (DFT) methods, and four hydrogen bridges [...] Read more.

In this work, we investigated an organic semiconductor based on zinc 8-hydroxyquinoline (ZnQ₂) and tetracyanoquinodimethane (TCNQ), which can be used as a photoactive layer in organic devices. The semiconductor was optimized by applying density-functional theory (DFT) methods, and four hydrogen bridges were formed between ZnQ₂ and TCNQ. Later, thin films of ZnQ₂-TCNQ were successfully deposited. The films were structurally and morphologically characterized, and the optical characteristics of the photoactive layer were investigated using ultraviolet–visible spectroscopy and time-dependent density-functional theory (TDDFT) calculations. The comparison and analysis of the experimental and theoretical absorption spectra indicate that the optical bandgap of the photoactive layer is 2.4 eV. Additionally, a flexible photo device was manufactured with the active layer ZnQ₂-TCNQ, and its electrical behavior was evaluated under dark and light conditions. The results show a significant change in the behavior of the device when radiation is eliminated; the layer is light sensitive. The electrical resistance in the flexible photo device is associated with the optical behavior of the materials that constitute the active layer. Full article

(This article belongs to the Special Issue Applications of Thin Films in Microelectronics)

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10 pages, 3058 KiB

Open AccessEditor’s ChoiceArticle

Electrical Performance and Stability Improvements of High-Mobility Indium–Gallium–Tin Oxide Thin-Film Transistors Using an Oxidized Aluminum Capping Layer of Optimal Thickness

by Hyun-Seok Cha, Hwan-Seok Jeong, Seong-Hyun Hwang, Dong-Ho Lee and Hyuck-In Kwon

Electronics 2020, 9(12), 2196; https://doi.org/10.3390/electronics9122196 - 20 Dec 2020

Cited by 11 | Viewed by 3216

Abstract

We examined the effects of aluminum (Al) capping layer thickness on the electrical performance and stability of high-mobility indium–gallium–tin oxide (IGTO) thin-film transistors (TFTs). The Al capping layers with thicknesses (t_Als) of 3, 5, and 8 nm were deposited, respectively, [...] Read more.

We examined the effects of aluminum (Al) capping layer thickness on the electrical performance and stability of high-mobility indium–gallium–tin oxide (IGTO) thin-film transistors (TFTs). The Al capping layers with thicknesses (t_Als) of 3, 5, and 8 nm were deposited, respectively, on top of the IGTO thin film by electron beam evaporation, and the IGTO TFTs without and with Al capping layers were subjected to thermal annealing at 200 °C for 1 h in ambient air. Among the IGTO TFTs without and with Al capping layers, the TFT with a 3 nm thick Al capping layer exhibited excellent electrical performance (field-effect mobility: 26.4 cm²/V s, subthreshold swing: 0.20 V/dec, and threshold voltage: −1.7 V) and higher electrical stability under positive and negative bias illumination stresses than other TFTs. To elucidate the physical mechanism responsible for the observed phenomenon, we compared the O1s spectra of the IGTO thin films without and with Al capping layers using X-ray photoelectron spectroscopy analyses. From the characterization results, it was observed that the weakly bonded oxygen-related components decreased from 25.0 to 10.0%, whereas the oxygen-deficient portion was maintained at 24.4% after the formation of the 3 nm thick Al capping layer. In contrast, a significant increase in the oxygen-deficient portion was observed after the formation of the Al capping layers having t_Al values greater than 3 nm. These results imply that the thicker Al capping layer has a stronger gathering power for the oxygen species, and that 3 nm is the optimum thickness of the Al capping layer, which can selectively remove the weakly bonded oxygen species acting as subgap tail states within the IGTO. The results of this study thus demonstrate that the formation of an Al capping layer with the optimal thickness is a practical and useful method to enhance the electrical performance and stability of high-mobility IGTO TFTs. Full article

(This article belongs to the Special Issue Applications of Thin Films in Microelectronics)

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10 pages, 1698 KiB

Open AccessEditor’s ChoiceCommunication

Effects of Annealing Atmosphere on Electrical Performance and Stability of High-Mobility Indium-Gallium-Tin Oxide Thin-Film Transistors

by Hwan-Seok Jeong, Hyun Seok Cha, Seong Hyun Hwang and Hyuck-In Kwon

Electronics 2020, 9(11), 1875; https://doi.org/10.3390/electronics9111875 - 07 Nov 2020

Cited by 11 | Viewed by 3439

Abstract

In this study, we examined the effects of the annealing atmosphere on the electrical performance and stability of high-mobility indium-gallium-tin oxide (IGTO) thin-film transistors (TFTs). The annealing process was performed at a temperature of 180 °C under N₂, O₂, [...] Read more.

In this study, we examined the effects of the annealing atmosphere on the electrical performance and stability of high-mobility indium-gallium-tin oxide (IGTO) thin-film transistors (TFTs). The annealing process was performed at a temperature of 180 °C under N₂, O₂, or air atmosphere after the deposition of IGTO thin films by direct current magnetron sputtering. The field-effect mobility (μ_FE) of the N₂- and O₂-annealed IGTO TFTs was 26.6 cm²/V·s and 25.0 cm²/V·s, respectively; these values were higher than that of the air-annealed IGTO TFT (μ_FE = 23.5 cm²/V·s). Furthermore, the stability of the N₂- and O₂-annealed IGTO TFTs under the application of a positive bias stress (PBS) was greater than that of the air-annealed device. However, the N₂-annealed IGTO TFT exhibited a larger threshold voltage shift under negative bias illumination stress (NBIS) compared with the O₂- and air-annealed IGTO TFTs. The obtained results indicate that O₂ gas is the most suitable environment for the heat treatment of IGTO TFTs to maximize their electrical properties and stability. The low electrical stability of the air-annealed IGTO TFT under PBS and the N₂-annealed IGTO TFT under NBIS are primarily attributed to the high density of hydroxyl groups and oxygen vacancies in the channel layers, respectively. Full article

(This article belongs to the Special Issue Applications of Thin Films in Microelectronics)

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10 pages, 1611 KiB

Open AccessEditor’s ChoiceArticle

Polarization-Charge Inversion at Al₂O₃/GaN Interfaces through Post-Deposition Annealing

by Kwangeun Kim and Jaewon Jang

Electronics 2020, 9(7), 1068; https://doi.org/10.3390/electronics9071068 - 30 Jun 2020

Cited by 4 | Viewed by 3652

Abstract

The effects of post-deposition annealing (PDA) on the formation of polarization-charge inversion at ultrathin Al₂O₃/Ga-polar GaN interfaces are assessed by the analysis of energy band bending and measurement of electrical conduction. The PDA-induced positive interface charges form downward energy [...] Read more.

The effects of post-deposition annealing (PDA) on the formation of polarization-charge inversion at ultrathin Al₂O₃/Ga-polar GaN interfaces are assessed by the analysis of energy band bending and measurement of electrical conduction. The PDA-induced positive interface charges form downward energy band bending at the Al₂O₃/GaN interfaces with polarization-charge inversion, which is analyzed using X-ray photoelectron spectroscopy. Net charge and interface charge densities at the Al₂O₃/GaN interfaces are estimated after PDA at 500 °C, 700 °C, and 900 °C. The PDA temperatures affect the formation of charge densities. That is, the charge density increases up to 700 °C and then decreases at 900 °C. Electrical characteristics of GaN Schottky diodes with ultrathin Al₂O₃ layers exhibit the passivation ability of the Al₂O₃ surface layer and the effects of polarization-charge inversion through PDA. This result can be applied to improvement in GaN-based electronic devices where surface states and process temperature work important role in device performance. Full article

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10 pages, 5232 KiB

Open AccessEditor’s ChoiceArticle

Effect of Mg Doping on the Electrical Performance of a Sol-Gel-Processed SnO₂ Thin-Film Transistor

by Won-Yong Lee, Hyunjae Lee, Seunghyun Ha, Changmin Lee, Jin-Hyuk Bae, In-Man Kang, Kwangeun Kim and Jaewon Jang

Electronics 2020, 9(3), 523; https://doi.org/10.3390/electronics9030523 - 22 Mar 2020

Cited by 16 | Viewed by 4374

Abstract

Sol-gel-processed Mg-doped SnO₂ thin-film transistors (TFTs) were successfully fabricated. The effect of Mg concentration on the structural, chemical, and optical properties of thin films and the corresponding TFT devices was investigated. The results indicated that an optimal Mg concentration yielded an improved [...] Read more.

Sol-gel-processed Mg-doped SnO₂ thin-film transistors (TFTs) were successfully fabricated. The effect of Mg concentration on the structural, chemical, and optical properties of thin films and the corresponding TFT devices was investigated. The results indicated that an optimal Mg concentration yielded an improved negative bias stability and increased optical band gap, resulting in transparent devices. Furthermore, the optimal device performance was obtained with 0.5 wt% Mg. The fabricated 0.5 wt% Mg-doped SnO₂ TFT was characterized by a field effect mobility, a subthreshold swing, and I_on/I_off ratio of 4.23 cm²/Vs, 1.37 V/decade, and ~1 × 10⁷, respectively. The added Mg suppressed oxygen-vacancy formation, thereby improving the bias stability. This work may pave the way for the development of alkaline-earth-metal-doped SnO₂-based thin-film devices. Full article

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8 pages, 3787 KiB

Open AccessFeature PaperArticle

Sol-Gel Processed Yttrium-Doped SnO₂ Thin Film Transistors

by Changmin Lee, Won-Yong Lee, Hyunjae Lee, Seunghyun Ha, Jin-Hyuk Bae, In-Man Kang, Hongki Kang, Kwangeun Kim and Jaewon Jang

Electronics 2020, 9(2), 254; https://doi.org/10.3390/electronics9020254 - 03 Feb 2020

Cited by 28 | Viewed by 4404

Abstract

Y-doped SnO₂ thin film transistors were successfully fabricated by means of sol-gel process. The effect of Y concentration on the structural, chemical, and electrical properties of sol-gel-processed SnO₂ films was investigated via GIXRD, SPM, and XPS; the corresponding electrical transport properties [...] Read more.

Y-doped SnO₂ thin film transistors were successfully fabricated by means of sol-gel process. The effect of Y concentration on the structural, chemical, and electrical properties of sol-gel-processed SnO₂ films was investigated via GIXRD, SPM, and XPS; the corresponding electrical transport properties of the film were also evaluated. The dopant, Y, can successfully control the free carrier concentration by suppressing the formation of oxygen vacancy inside SnO₂ semiconductors due to its lower electronegativity and SEP. With an increase of Ywt%, it was observed that the crystallinity and oxygen vacancy concentration decreased, and the operation mode of SnO₂ thin film transistor changed from accumulation (normally on) to enhancement mode (normally off) with a positive V_th shift. Full article

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9 pages, 2742 KiB

Open AccessArticle

Effect of Annealing Ambient on SnO₂ Thin Film Transistors Fabricated via An Ethanol-based Sol-gel Route

by Hyunjae Lee, Seunghyun Ha, Jin-Hyuk Bae, In-Man Kang, Kwangeun Kim, Won-Yong Lee and Jaewon Jang

Electronics 2019, 8(9), 955; https://doi.org/10.3390/electronics8090955 - 29 Aug 2019

Cited by 17 | Viewed by 3815

Abstract

The effect of annealing ambient on SnO₂ thin-film transistors (TFTs) fabricated via an ethanol-based sol-gel route was investigated. The annealing ambient has a significant effect on the structural characteristics and chemical composition and, in turn, the device performance. Although the crystalline-grain size [...] Read more.

The effect of annealing ambient on SnO₂ thin-film transistors (TFTs) fabricated via an ethanol-based sol-gel route was investigated. The annealing ambient has a significant effect on the structural characteristics and chemical composition and, in turn, the device performance. Although the crystalline-grain size of the SnO₂ films annealed in air was the smallest, this size yielded the highest field-effect mobility. Compared with the minimization of boundary scattering via crystalline-size increase, augmentation of the free carrier concentration played a more critical role in the realization of high-performance devices. The fabricated SnO₂ TFTs delivered a field-effect mobility, subthreshold swing, and on/off current ratio of 10.87 cm²/Vs, 0.87 V/decade, and 10⁷, respectively. Full article

(This article belongs to the Special Issue Applications of Thin Films in Microelectronics)

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8 pages, 2995 KiB

Open AccessArticle

Effect of Annealing Environment on the Performance of Sol–Gel-Processed ZrO₂ RRAM

by Seunghyun Ha, Hyunjae Lee, Won-Yong Lee, Bongho Jang, Hyuk-Jun Kwon, Kwangeun Kim and Jaewon Jang

Electronics 2019, 8(9), 947; https://doi.org/10.3390/electronics8090947 - 28 Aug 2019

Cited by 21 | Viewed by 4157

Abstract

We investigate the annealing environment effect on ZrO₂-based resistive random-access memory (RRAM) devices. Fabricated devices exhibited conventional bipolar-switching memory properties. In particular, the vacuum-annealed ZrO₂ films exhibited larger crystallinity and grain size, denser film, and a relatively small quantity of [...] Read more.

We investigate the annealing environment effect on ZrO₂-based resistive random-access memory (RRAM) devices. Fabricated devices exhibited conventional bipolar-switching memory properties. In particular, the vacuum-annealed ZrO₂ films exhibited larger crystallinity and grain size, denser film, and a relatively small quantity of oxygen vacancies compared with the films annealed in air and N₂. These led to a decrease in the leakage current and an increase in the resistance ratio of the high-resistance state (HRS)/low-resistance state (LRS) and successfully improved non-volatile memory properties, such as endurance and retention characteristics. The HRS and LRS values were found to last for 10⁴ s without any significant degradation. Full article

(This article belongs to the Special Issue Applications of Thin Films in Microelectronics)

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Review

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19 pages, 55977 KiB

Open AccessReview

Ferroelectrics Based on HfO₂ Film

by Chong-Myeong Song and Hyuk-Jun Kwon

Electronics 2021, 10(22), 2759; https://doi.org/10.3390/electronics10222759 - 11 Nov 2021

Cited by 11 | Viewed by 8488

Abstract

The discovery of ferroelectricity in HfO₂ thin film, which is compatible with the CMOS process, has revived interest in ferroelectric memory devices. HfO₂ has been found to exhibit high ferroelectricity at a few nanometers thickness, and studies have rapidly progressed in [...] Read more.

The discovery of ferroelectricity in HfO₂ thin film, which is compatible with the CMOS process, has revived interest in ferroelectric memory devices. HfO₂ has been found to exhibit high ferroelectricity at a few nanometers thickness, and studies have rapidly progressed in the past decade. Ferroelectricity can be induced in HfO₂ by various deposition methods and heat treatment processes. By combining ferroelectric materials with field-effect transistors, devices that combine logic and memory functions can be implemented. Ferroelectric HfO₂-based devices show high potential, but there are some challenges to overcome in endurance and characterization. In this paper, we discuss the fabrication and characteristics of ferroelectric HfO₂ film and various applications, including negative capacitance (NC)), Ferroelectric random-access memory (FeRAM), Ferroelectric tunnel junction (FTJ), and Ferroelectric Field-effect Transistor (FeFET). Full article

(This article belongs to the Special Issue Applications of Thin Films in Microelectronics)

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