Tunable Microwave Filters Using HfO2-Based Ferroelectrics

Aldrigo, Martino; Dragoman, Mircea; Iordanescu, S.; Nastase, F.; Vulpe, Silviu

doi:10.3390/nano10102057

Cited by 15 publications

(14 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In particular, Hf ZrO has a roughness of 0.2-0.3 nm, [30] whereas this parameter is 0.4-0.6 nm in the case of hexagonal boron-nitride [31] and is bigger, around 1 nm, for SiO 2 . [32] Moreover, Hf ZrO is not only among the best substrates to transfer on graphene monolayers grown by CVD at the wafer scale, but, as we have shown very recently theoretically [33] and experimentally, [34] Hf ZrO is opening a bandgap in graphene, conferring switching properties to [29] Copyright 2019, The Authors, published by MDPI. Reproduced under the terms of the CC-BY Creative Commons Attribution 4.0 International license (https://creativecommons.org/ licenses/by/4.0).…”

Section: D Materials/hf Zro Heterostructuresmentioning

confidence: 82%

“…The error bars in both Figure 17 and 18 were considered International license (https://creativecommons.org/licenses/by/4.0). [29] Copyright 2019, The Authors, published by MDPI. and d) FET electrodes deposition.…”

Section: D Materials/hf Zro Heterostructuresmentioning

confidence: 99%

“…Very recently, we have shown that microwave filters based on a 6‐nm‐thick HfZrO layer are tunable in the range 0.1–16 GHz by varying the DC voltage in the range 0–4 V. [ 29 ] Three filter configurations: low‐pass filter (LPF), high‐pass filter (HPF), and band‐pass filter (BPF) were designed, fabricated, and measured, showing a frequency shift of the minimum of the reflection coefficient between 90 MHz and 4.4 GHz, with a minimum insertion loss of about 6.9 dB in the high‐pass configuration. The filters are shown in Figure .…”

Section: Microwave Devices Based On Hfzromentioning

confidence: 99%

“…Transmission coefficient |S 21 | for the HPF at 3 V. Reproduced under the terms of the CC‐BY Creative Commons Attribution 4.0 International license ( https://creativecommons.org/licenses/by/4.0). [ 29 ] Copyright 2019, The Authors, published by MDPI.…”

Section: Microwave Devices Based On Hfzromentioning

confidence: 99%

See 3 more Smart Citations

HfO₂‐Based Ferroelectrics Applications in Nanoelectronics

Dragoman

Aldrigo

Dragoman

et al. 2021

Physica Rapid Research Ltrs

Self Cite

View full text Add to dashboard Cite

In memoriam of Prof. Dan Dascalu IntroductionHafnium oxide (HfO 2 ) is the dielectric commonly used in fieldeffect transistors (FETs) fabricated in complementary metal oxide semiconductor (CMOS) technologies and, as such, retrieved in any very large-scale integrated (VLSI) circuits. Examples of such circuits include microprocessors or complex analog integrated circuits found in daily applications, for instance, in computers, smartphones, laptops, or incorporated in cars, airplanes, or medical equipments. Since the discovery of HfO 2 as a dielectric for modern integrated circuits, increasing its permittivity was a leading research issue in itself because higher permittivity values allow decreasing the effective oxide thickness (EOT), and so the leakage current; this is especially important when billions of Si FETs are integrated on a single chip. The solution found to boost the permittivity of HfO 2 is represented by structural phase transformations. [1] HfO 2 has its lowest electrical permittivity (ε r % 18) in its stable phase, which is the monoclinic phase. Higher permittivity values, of ε r % 27 in the cubic phase and ε r % 70 in the tetragonal phase, are achieved, nonetheless, in phases that are stable only at very high temperatures, exceeding 1700 C. The decrease in these temperatures is possible, however, by HfO 2 doping. Thus, the cubic and the tetragonal phases were first obtained at lower temperatures via Y doping [1] and, respectively, Si doping, [2] whereas a stable HfO 2 tetragonal phase at nearly room temperature was observed by growing HfO 2 via atomic layer deposition (ALD) and doping it with ZrO 2 . [3,4] As described in the recent review, [5] the stabilization of these phases is determined by the concentration of dopants, the annealing temperature, and the growing methods.These initial investigations focused on increasing the permittivity of HfO 2 lead eventually to the discovery of the orthorhombic phase of HfO 2 , which was associated with HfO 2 ferroelectricity. [6,7] This phase is obtained under different growth conditions in the presence of dopants, including those mentioned earlier, and requires strict control of dopant concentration, temperature, and mechanical strain. The most used orthorhombic HfO 2 -based ferroelectric, named further as Hf ZrO, is doped with Zr and is usually grown at the wafer level, up to 300 mm, using ALD. It thus benefits from the state-of-the-art CMOS technology. More recently, using Zr-doping and pulsed laser deposition (PLD), another rhombohedral phase of HfO 2 was discovered to be also ferroelectric. [7] The rhombohedral or orthorhombic Hf ZrO are ferroelectrics with similar electric performances; the origin of stable ferroelectricity in both cases being due to the induced strain between the top and/or down substrates sandwiching Hf ZrO. [8] Doping or strain application modifies the atomic structure of a material and can induce a phase transition, in particular can induce ferroelectricity in HfO 2 . Similarly, HfO 2 can transform into a weak magnetic material [9...

show abstract

Section: D Materials/hf Zro Heterostructuresmentioning

confidence: 82%

Section: D Materials/hf Zro Heterostructuresmentioning

confidence: 99%

Section: Microwave Devices Based On Hfzromentioning

confidence: 99%

Section: Microwave Devices Based On Hfzromentioning

confidence: 99%

See 2 more Smart Citations

HfO₂‐Based Ferroelectrics Applications in Nanoelectronics

Dragoman

Aldrigo

Dragoman

et al. 2021

Physica Rapid Research Ltrs

Self Cite

View full text Add to dashboard Cite

show abstract

“…Varactors, based on ferroelectric HZO interdigitated capacitors were first proposed by Dragoman group [12][13][14][15][16]. We have also proposed the use of CMOS compatible devices in the BEoL, based on HZO varactors in a parallel-plate MFM configuration [17,18], but due to the lack of experimental data at high frequencies, the dielectric relaxation was not considered.…”

Section: Introductionmentioning

confidence: 99%

RF-Characterization of HZO Thin Film Varactors

Abdulazhanov

Huynh

et al. 2021

Crystals

View full text Add to dashboard Cite

A microwave characterization at UHF band of a ferroelectric hafnium zirconium oxide metal-ferroelectric-metal (MFM) capacitors for varactor applications has been performed. By using an impedance reflectivity method, a complex dielectric permittivity was obtained at frequencies up to 500 MHz. Ferroelectric Hf0.5Zr0.5O2 of 10 nm thickness has demonstrated a stable permittivity switching in the whole frequency range. A constant increase of the calculated dielectric loss is observed, which is shown to be an effect of electric field distribution on highly resistive titanium nitride (TiN) thin film electrodes. The C-V characteristics of a “butterfly” shape was also extracted, where the varactors exhibited a reduction of capacitance tunability from 18.6% at 10 MHz to 15.4% at 500 MHz.

show abstract