Lead Niobate-based Tunable Dielectrics for Smart Microwave and Millimeter-wave Systems

Lead Research Organisation: University of Southampton
Department Name: School of Chemistry

Abstract

Electronically beam-steerable array antennas (phased arrays or smart antennas) at microwave and millimetre-wave (mm-wave) frequencies are extremely important for various wireless systems including satellite communications, terrestrial mobile communications, radars, "Internet Of Things", wireless power transmission, satellite navigations and deep-space communication. Traditionally, beam steering of antenna is achieved by moving the reflector mechanically, which is slow, bulky and not reliable. Phased arrays, which integrate antennas and phase shifter circuits, are an attractive alternative to gimbaled parabolic reflectors as they offer rapid beam steering towards the desired targets and better reliability. Phase shifters are critical components in phased arrays as the beam steering is achieved by controlling phase shifters electronically.

A promising research direction to create small, fast, reliable phase shifters with low insertion loss at high frequency is the use of tunable dielectric materials due to its potential of monolithic fabrication of array antennas and circuits. A breakthrough in such materials came recently when we demonstrated that Lead Niobate Pyrochlores PbnNb2O5+n gives the best combination of dielectric constant, tunability and low loss of any known thin film system. Translating these superior materials properties into actual device performance and high-performance electronically beam-steerable arrays antennas at microwave and mm-wave bands are the key aims of this project

Planned Impact

The proposed program aims to find tunable dielectric materials which have low loss and high tunability for meeting the requirements of future wireless communication systems where all RF/microwave/millimeter-wave components and circuits need to be "tuneable". To investigate the performance of the materials in practical devices, circuits and sub-systems, tuneable dielectric will then be applied into microwave and millimeter-wave phase shifter circuits and phased arrays. Phased arrays, due to advantages of electronically beam steering and high gain, are the critical technology for next-generation mobile communications (5G), broadband satellite communications and radar systems.

The general public and communication service subscribers will benefit from broadband multimedia services with enhanced efficiency, speed, range, performance and sustainability.

This research facilitates generation of innovative applications in communication systems, benefits the communications industry with low cost improvements to the wireless link and enhances the UK's economic competiveness. The research finds will also be useful for UK national security and defence as the phased arrays will increase the performance of radars significantly.

Our industrial partners Ilika plc, BAE Systems, Keysight Technologies, Rohde Schwarz, Huawei Technologies UK Ltd, and NEC Europe have expressed their strong interests in the proposed project. Their involvement is a valuable asset for our project due to their strong focus on research and development, early deployment and commercial exploitation capabilities.

Public engagement activities will ensure a wider education of the population concerning the importance of materials in advanced technology in everyday lives.

Publications

10 25 50
 
Description 5G communications are based on the transmission of a signal from one device to another at high frequencies. The devices that are widely used such as antennas, navigation systems and cell phones use capacitors which store electric energy. The capacitors are composed of insulating materials which are called dielectrics. The quality of the dielectric will determine the losses when a signal is transmitted.
In this research we have focused on the elimination of losses at high frequencies in order to make 5G communications more reliable, fast and effective. Our strategy was based on the improvement of the dielectric materials but also on the design and better performance of the devices that transfer the signal (waveguides and antennas). We have grown high quality thin films with high though put physical vapor deposition (HT-PVD). This method is based on the evaporation of sources (chemical elements) and results in the formation of numerous compositions in very short time.
Using HT-PVD we managed to identify the best compositions of a known system ,called BaTiO3, that resulted in lower losses when doped with small amount of Mn. We have fabricated an array of devices on small chips (35 mm x 35 mm)and compared their performance at high frequencies. We investigated the electric properties of alternative materials called pyroclores which showed low losses.
Our key findings can be summarized to the following:
1) we proved the high throughput growth and screening of capacitive devices at high frequencies
2) Investigated and achieved the in situ growth of ubic crystalline PbNbO and Bi-doped PbNbO.
3) Measured electric properties at room temperature of PbNbO and Bi-doped PbNbO.
Exploitation Route The elimination of losses on dielectric materials at high frequencies has been a known and challenging problem for many decades. Our strategy to address this problem is based on a multidisciplinary approach based on the synergy of scientists with backgrounds from applied materials science to cutting edge engineering research. The results of this work can have a useful impact on the academic society as it will lead on the discovery of new compositions of materials with excellent dielectric properties. The integration of these materials in devices will provide critical information about the maximum performance of the devices at high frequencies. These findings can be used by companies whose products and devices for high frequency communication systems such as Huawei, Murata etc.
Sectors Digital/Communication/Information Technologies (including Software),Electronics,Energy,Other

 
Title Development of probe station for the highthrouput characterization of dielectric properties 
Description An experimental set up is currently being developed for the electrical measurements of the dielectric thin films fabricated. The experimental set up, herafter refferred to as 'probe station' allows the electric characterization as it measures the dielectric tunability of the thin films, the Seebeck coefficient the current -voltage loops etc. 
Type Of Material Improvements to research infrastructure 
Year Produced 2018 
Provided To Others? No  
Impact High Throughput mapping of the dielectric properties of the thin films. 
 
Title Donation from Ilika Technologies( £3.4M) of Combinatorial Synthesis and Characterisation Tools to ACMF 
Description Donation of new High Thoughput-Physical Vapor Deposition (HT-PVD) System and HT characterization tools. Specifically the list of instruments that has been donated includes the following: HT-PVD (Purchase price £2,000,000, Age/years 11) SEM/EDX (Purchase price £140,000, Age/Years 8) XRD (Purchase price £240,000,Age/Years 10) Probe Station (Purchase price £106,000, Age/Years 11) HT-XPS (Purchase price £94,000, Age/Years 10) Spectroscopic Ellispometer (Purchase price £102,000 Age/Years 11) Optical Profilometer (Purchase price £65,000, Age/Years 11) 8 XRD £240,000 10 Probe Station £106,000 11 HT-XPS £94,000 10 Spectroscopic Ellipsometer £102,000 11 Optical Profilometer £65,000 13 
Type Of Material Improvements to research infrastructure 
Year Produced 2019 
Provided To Others? Yes  
Impact Improvement of infrastructure of the Advanced Composite Materials Facility besed in Chemistry Southampton. These instruments are accessible for other research teams as well. 
 
Description Collaboration with Zepler Insitute and Prof. Goran Mashanovich for the growth of large Pockels coeffiecient Pb(ZrTi)O3 and BaTiO3 on Si substrates 
Organisation Zepler Institute
Country United Kingdom 
Sector Academic/University 
PI Contribution The ACMF team (Prof. Hayden and Dr. Bakaimi) have recently demonstrated the high throughput growth of BaTiO3 on Pt coated waveguides in order to increase the band width of high frequency electronic devices. The findings of this research have attracted interest from engineers of the Zepler Institute who focus on the fabrication of efficient and cost effective Si optical phase shifters based on the Pockels effect. Dr. Bakaimi is applying the combinatorial synthesis and characterization to grow efficient PZT optical phase shifters on Si substrates. Prof Hayden has provided access to the ACMF facility where no facility charge is levied in order to establish the groundwork for a follow on EPSRC proposal.
Collaborator Contribution The collaboration with Prof. Mashanovic and the Zepler Institute has started on October 2019 and has been funded by the EPSRC photonics hub on December 2019 with a budget of £50.000. The experimental work (starting on March 2020) of this project aims to prove the combinatorial growth and characterization of BaTiO3 and Pb(ZrTiO3) optical phase shifters on Si to achieve large Pockels coefficients. The Zepler Institute partners (Prof. Mashanovich, Dr. Cao Wei) will evaluate the phase shifters in terms of their DC and RF performance and the Pockels coefficient will be estimated. This is important as it will confirm high quality HT-­ePVD growth on SOI which will represent a very significant milestone and be used as preliminary work for an EPSRC proposal on high efficiency Si optical modulators that we would submit later in 2020. Rockley Photonics has expressed their enthusiastic support with an in kind contribution of £13,000 after Prof. Mashanovich has explained the significance of this project.
Impact The project starts on 14/3/2020/ therefore there is no outcome yet to report. This collaboration is multidisciplinary as it stems from the need to improve the efficiency of low power silicon photonic phase shifters through the optimazation of the material that is used in order to obtain the large Pockels coeffient. Therefore it is an exceptional example of applied materials science towards the requirements of cutting edge engineering research.
Start Year 2019
 
Description Ilika Technologies Ltd 
Organisation BAE Systems
Country United Kingdom 
Sector Academic/University 
PI Contribution Use of facilities for the synthesis of BST based libraries, and analytical facilities.
Collaborator Contribution Designs for waveguide fabrication.
Impact No output yet
Start Year 2016
 
Description Ilika Technologies Ltd 
Organisation Huawei Technologies
Country China 
Sector Private 
PI Contribution Use of facilities for the synthesis of BST based libraries, and analytical facilities.
Collaborator Contribution Designs for waveguide fabrication.
Impact No output yet
Start Year 2016
 
Description Ilika Technologies Ltd 
Organisation Ilika
Department Ilika Technologies Ltd.
Country United Kingdom 
Sector Private 
PI Contribution Use of facilities for the synthesis of BST based libraries, and analytical facilities.
Collaborator Contribution Designs for waveguide fabrication.
Impact No output yet
Start Year 2016
 
Description Ilika Technologies Ltd 
Organisation Keysight Technologies
Country United States 
Sector Private 
PI Contribution Use of facilities for the synthesis of BST based libraries, and analytical facilities.
Collaborator Contribution Designs for waveguide fabrication.
Impact No output yet
Start Year 2016
 
Description Ilika Technologies Ltd 
Organisation Rohde and Schwarz
Country Germany 
Sector Private 
PI Contribution Use of facilities for the synthesis of BST based libraries, and analytical facilities.
Collaborator Contribution Designs for waveguide fabrication.
Impact No output yet
Start Year 2016
 
Title DetectColumns 
Description This program has been designed to analyze the intensity of atom columns in ADF-STEM images. 
Type Of Technology Software 
Year Produced 2018 
Impact Intensity of atom columns in ADF-STEM images can be analysed by this software. For instance, the resulting data of this program can reveal presence of atom site swapping, dopants, vacancies, etc. in the structure of materials. Using this software, we resolved light atoms (e.g. oxygen) in the ADF images obtain from oxides containing relatively heavy atoms. 
URL https://www.researchgate.net/publication/320673454_DetectColumns_Program
 
Title Development of LabView Software for the HighThrouput Screening of the Thin Films Electrical Measurements 
Description We have developed a Labview programme for the screening of electrical properties such as measurement of capacitance versus an applied electric field which is necessary in order to characterize tunable dielectrics. Software is under development for obtaining other electric properties such as Seebeck coefficient. 
Type Of Technology Software 
Year Produced 2018 
Impact It is essential for the dielectric properties combinatorial screening of the fabricated thin films.