Tunable barium strontium titanate thin film capacitors for RF and microwave applications

Tombak, A.; Maria, Jon Paul; Ayguavives, F.; Zhang, Jin; Stauf, Gregory T.; Kingon, Angus I.; Mortazawi, Amir

doi:10.1109/7260.975716

Cited by 167 publications

(65 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…From the 2θ XRD data for the (002) peak, the out-of-plane (OOP) lattice parameters of BST and LSMO layer are determined as 3.956A • and 3.843A • , respectively. These are very close to the bulk lattice parameters of BST (3.965A • ) [1][2][3][4][5][6][7] and LSMO (3.870A • ) 12,13 layers. The estimated strain for BST and LSMO layers along the c-direction is ∼0.2% and 0.7%, respectively, which is attributed to unrelaxed thermal and defect-induced strain, and some additional unrelaxed lattice mismatch strain for the BST (delete LSMO and insert BST) layer grown on the LSMO (delete BST and insert LSMO).…”

Section: Resultssupporting

confidence: 55%

“…The magnetic response is not saturated under a 300 Oe field, hence, it is expressed only in magnetic moment (emu), not in emu/cc. [1][2][3][4][5][6][7] The enhancements in H c and H EB at low temperature appears to be directly related to the ferroelectric nature of BST layer, and the resulting strain (∼0.4%) and/or charge redistributions that take place as the BST layer transformed from the cubic (paraelectric) to tetragonal (ferroelectric) phase at low temperature (200K). 18 This may also be consistent with the number of previous reports [19][20][21][22] on the formation of an antiferromagnetic region or layer due to strong pinned spins and magnetic depletion layer observed at various ferromagnetic and ferroelectric interfaces.…”

Section: Fig 2 Magnetic Moment Vs Temperature (M-t) Curves Of Lsmomentioning

confidence: 99%

“…For this study a concentration of Ba 0.4 Sr 0.6 TiO 3 (BST) is chosen, which is cubic and paraelectric at the (delete) ambient temperature, and then transforms to a ferroelectric tetragonal phase upon cooling through the Curie temperature (T C ) at 200K. 4 Previous workers [1][2][3][4][5][6][7] have deposited BST thin films on oxide substrates such as MgO, LaAlO 3 , SrTiO 3 , and Al 2 O 3 . However, high single crystal cost and small size are their (delete) major drawbacks of such substrates.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Exchange bias in Ba0.4Sr0.6TiO3/La0.7Sr0.3MnO3 heterostructures

2017

View full text Add to dashboard Cite

This work relates to the integration of the two-layer stack of the proposed multiferroic structure onto silicon substrates. Ba1-xSrxTiO3 is an excellent material for room-temperature voltage-tunable dielectric applications due to its high (ε=6000) dielectric constant. In this study we choose a composition of Ba0.4Sr0.6TiO3 (BST), which is cubic and paraelectric at 300K, and transforms to a ferroelectric tetragonal phase upon cooling through the Curie temperature (TC) at 200K. The main focus of the present work is to study what happens when BST is placed in contact with a room temperature ferromagnetic layer such as La0.7Sr0.3MnO3 (LSMO). In this study, the magnetic properties of a BST (200nm)/LSMO (63nm) heterostructure was compared to that of a single LSMO layer (63nm). Both films were deposited onto MgO/TiN buffered Si (100) using pulsed laser deposition (PLD) and a domain matching epitaxy (DME) paradigm. X-ray diffraction (XRD) measurements showed that these films were of single phase and epitaxial in nature, with an unrelaxed lattice strain of ∼0.2% that was predominately composed of thermal and defect-induced strain. The magnetic measurements showed that the Curie temperature (TC) of LSMO remained unchanged at 350K when the BST was in contact with the LSMO layer. Interestingly, at 4K both the coercive field (Hc) and the exchange bias (HEB) of the BST/LSMO heterostructure as compared to the lone LSMO film increased significantly from 400 to 800 Oe and from 155 to 305 Oe, respectively. These differences were found to disappear above 200 K, the ferroelectric TC of the BST over-layer. This strongly suggests that the observed changes in the magnetic behavior of the heterostructure was the result of stress and/or charge redistributions that resulted when the BST layer transformed from the cubic (paraelectric) to tetragonal (ferroelectric) phase at low temperature.

show abstract

Section: Resultssupporting

confidence: 55%

Section: Fig 2 Magnetic Moment Vs Temperature (M-t) Curves Of Lsmomentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Exchange bias in Ba0.4Sr0.6TiO3/La0.7Sr0.3MnO3 heterostructures

2017

View full text Add to dashboard Cite

show abstract

“…Varactor diodes are able to provide a capacitance tuning ratio of 5:1 or higher when reverse-biased up to 20 V. Previous work has shown that, for slot loop antennas with varactor-diode loading, more than 20% frequency tuning range can be achieved [1,4]. On the other hand, despite of their high quality factor and good power handling capability [8], ferroelectric varactors usually have lower capacitance tuning ratio (often biased below 3:1 voltage for reliable operation) when compared to semiconductor-based varactor diodes. Therefore, the reported tuning range of ferroelectric-based reconfigurable antennas is mostly lower than that of their diode-based counterparts.…”

Section: Introductionmentioning

confidence: 99%

A frequency-reconfigurable slot loop antenna using ferroelectric MIM capacitors

Chen

et al. 2013

IEICE Electron. Express

View full text Add to dashboard Cite

A frequency-reconfigurable antenna based on periodically loading ferroelectric MIM capacitors along a slot loop is designed, fabricated, and measured. The antenna is fabricated on a 430-m-thick sapphire substrate with a total area of 1×1 cm 2 . The size of the slot loop is 2.5×2.5 mm 2 . By changing the bias voltage of the ferroelectric varactors from 0 V to 7 V, the resonant frequency of the varactor-loaded antenna can be tuned from 5.57 GHz to 7.33 GHz, corresponding to a tuning range of 27.3%, while keeping the return loss greater than 10 dB. At 5.57 GHz, the size of the slot loop is 0.046×0.046 0 2 . When biased at 7 V, the antenna gain is À10.8 dBi at 7.35 GHz. Under 0-V bias, the P in,1 dB of the tunable antenna is 18.8 dBm at 5.6 GHz.

show abstract

“…The tunable microwave components are such as semiconductor varactors, MEMs varactors and ferroelectric varactors [2]. Thin film ferro-electric can be beneficial in tunable RF and microwave components such as voltage controlled oscillators, tunable filters and phase shifters [3]. Tunable capacitors using ferroelectric thin film have two conventional structures; parallel plates and interdigital capacitors (IDC) [4].…”

Section: Introductionmentioning

confidence: 99%

Modelling the inhomogenity of the ferroelectric layer in a multilayered IDC

Ramezanpour

Nikmehr

Ghanbari

2013

IEICE Electron. Express

View full text Add to dashboard Cite

Abstract:In this paper the average value between the electric fields, in the ferroelectric layer is assigned to the electric field of the ferroelectric layer. This method reveals good performance for low value of the ferroelectric thicknesses. Furthermore a more precise method is proposed in which the ferroelectric layer is divided into the one region at the gap between the strips and two regions below the strips and constant relative permittivities are assigned to these regions. Applying the method for the structures with different dimensions, approves the accuracy of the method.

show abstract

Tunable barium strontium titanate thin film capacitors for RF and microwave applications

Cited by 167 publications

References 10 publications

Exchange bias in Ba0.4Sr0.6TiO3/La0.7Sr0.3MnO3 heterostructures

Exchange bias in Ba0.4Sr0.6TiO3/La0.7Sr0.3MnO3 heterostructures

A frequency-reconfigurable slot loop antenna using ferroelectric MIM capacitors

Modelling the inhomogenity of the ferroelectric layer in a multilayered IDC

Contact Info

Product

Resources

About