Design and Fabrication of 3.5 GHz Band-Pass Film Bulk Acoustic Resonator Filter.

With the development of wireless communication, increasing signal processing presents higher requirements for radio frequency (RF) systems. Piezoelectric acoustic filters, as important elements of an RF front-end, have been widely used in 5G-generation systems. In this work, we propose a Sc0.2Al0.8N-based film bulk acoustic wave resonator (FBAR) for use in the design of radio frequency filters for the 5G mid-band spectrum with a passband from 3.4 to 3.6 GHz. With the excellent piezoelectric properties of Sc0.2Al0.8N, FBAR shows a large Keff2 of 13.1%, which can meet the requirement of passband width. Based on the resonant characteristics of Sc0.2Al0.8N FBAR devices, we demonstrate and fabricate different ladder-type FBAR filters with second, third and fourth orders. The test results show that the out-of-band rejection improves and the insertion loss decreases slightly as the filter order increases, although the frequency of the passband is lower than the predicted ones due to fabrication deviation. The passband from 3.27 to 3.47 GHz is achieved with a 200 MHz bandwidth and insertion loss lower than 2 dB. This work provides a potential approach using ScAlN-based FBAR technology to meet the band-pass filter requirements of 5G mid-band frequencies.

Design and Fabrication of a Film Bulk Acoustic Wave Filter for 3.0 GHz-3.2 GHz S-Band.

Film bulk acoustic-wave resonators (FBARs) are widely utilized in the field of radio frequency (RF) filters due to their excellent performance, such as high operation frequency and high quality. In this paper, we present the design, fabrication, and characterization of an FBAR filter for the 3.0 GHz-3.2 GHz S-band. Using a scandium-doped aluminum nitride (Sc0.2Al0.8N) film, the filter is designed through a combined acoustic-electromagnetic simulation method, and the FBAR and filter are fabricated using an eight-step lithographic process. The measured FBAR presents an effective electromechanical coupling coefficient (keff2) value up to 13.3%, and the measured filter demonstrates a -3 dB bandwidth of 115 MHz (from 3.013 GHz to 3.128 GHz), a low insertion loss of -2.4 dB, and good out-of-band rejection of -30 dB. The measured 1 dB compression point of the fabricated filter is 30.5 dBm, and the first series resonator burns out first as the input power increases. This work paves the way for research on high-power RF filters in mobile communication.

Functional Analyses of the Bacillus velezensis HMB26553 Genome Provide Evidence That Its Genes Are Potentially Related to the Promotion of Plant Growth and Prevention of Cotton Rhizoctonia Damping-Off.

Bacillus spp. is one kind of the important representative biocontrol agents against plant diseases and promoting plant growth. In this study, the whole genomic sequence of bacterial strain HMB26553 was obtained. A phylogenetic tree based on the genome and ANI (average nucleotide identity), as well as dDDH (digital DNA-DNA hybridization), was constructed, and strain HMB26553 was identified as Bacillus velezensis. Fourteen biosynthetic gene clusters responsible for secondary metabolite were predicted via anti-SMASH, and six secondary metabolites were identified by UHPLC-QTOF-MS/MS (ultra-high-performance liquid chromatography coupled to quadrupole-time-of-flight tandem mass spectrometry). When the phytopathogen Rhizoctonia solani was treated with B. velezensis HMB26553, the mycelial structure changed, ROS (reactive oxygen species) accumulated, and the mitochondrial membrane potential decreased. Characteristics of strain HMB26553 were predicted and confirmed by genomic information and experiments, such as producing IAA, siderophore, extracellular enzymes and biofilm, as well as moving and promoting cotton growth. All these results suggested the mechanisms by which B. velezensis HMB26553 inhibits pathogen growth and promotes cotton growth, which likely provided the potential biocontrol agent to control cotton Rhizoctonia damping-off.

Preparation, Characterization, and Application of AlN/ScAlN Composite Thin Films.

Piezoelectric aluminum nitride (AlN) thin film, as a commonly used material for high-frequency acoustic resonators, has been a research hotspot in the RF field. Doping Sc elements in AlN is one of most effective methods to improve the piezoelectricity of the material. In this work, the first principal calculation and Mori-Tanaka model are used to obtain the piezoelectric constants of AlN, ScAlN, and AlN/ScAlN composites. Then, five types of AlN/ScAlN thin films are prepared on 8 inch silicon substrates. The crystal quality, roughness, and stress distribution are measured to characterize the film quality. The results show that composite film can effectively solve the problem of abnormal grains and reduce the roughness. Finally, a lamb wave resonator with an AlN/Sc0.2Al0.8N composite working at 2.33 GHz is fabricated. The effective electromechanical coupling coefficient Keff2 is calculated to be 6.19%, which has the potential to design high-frequency broadband filters.

Aluminum Nitride-Based Adjustable Effective Electromechanical Coupling Coefficient Film Bulk Acoustic Resonator.

The arrival of the 5G era has promoted the need for filters of different bandwidths. Thin-film bulk acoustic resonators have become the mainstream product for applications due to their excellent performance. The Keff2 of the FBAR greatly influences the bandwidth of the filter. In this paper, we designed an AlN-based adjustable Keff2 FBAR by designing parallel capacitors around the active area of the resonator. The parallel capacitance is introduced through the support column structure, which is compatible with conventional FBAR processes. The effects of different support column widths on Keff2 were verified by finite element simulation and experimental fabrication. The measured results show that the designed FBAR with support columns can achieve a Keff2 value that is 25.9% adjustable.

Aluminum scandium nitride thin-film bulk acoustic resonators for 5G wideband applications.

Bulk acoustic wave (BAW) filters have been extensively used in consumer products for mobile communication systems due to their high performance and standard complementary metal-oxide-semiconductor (CMOS) compatible integration process. However, it is challenging for a traditional aluminum nitride (AlN)-based BAW filter to meet several allocated 5G bands with more than a 5% fractional bandwidth via an acoustic-only approach. In this work, we propose an Al0.8Sc0.2N-based film bulk acoustic wave resonator (FBAR) for the design of radio frequency (RF) filters. By taking advantage of a high-quality Al0.8Sc0.2N thin film, the fabricated resonators demonstrate a large K eff 2 of 14.5% and an excellent figure of merit (FOM) up to 62. The temperature coefficient of frequency (TCF) of the proposed resonator is measured to be -19.2 ppm/°C, indicating excellent temperature stability. The fabricated filter has a center frequency of 4.24 GHz, a -3 dB bandwidth of 215 MHz, a small insertion loss (IL) of 1.881 dB, and a rejection >32 dB. This work paves the way for the realization of wideband acoustic filters operating in the 5G band.

Insights into complex infection by two Pectobacterium species causing potato blackleg and soft rot.

Pectobacterium spp. are causative agents of blackleg and soft rot of potato. However, little is known about the relationship between the pathogenicity of mixed infections of different Pectobacterium spp. at different temperatures. In this study, two pectinolytic strains of Pectobacterium spp. were isolated from the same potato plant with typical symptoms of blackleg and identified as P. brasiliense and P. carotovorum by multilocus sequence analysis (MLSA), whole-genome phylogenetic tree construction, average nucleotide identity (ANI) analysis and digital DNA-DNA hybridization (dDDH). Plant cell wall degrading enzyme, including pectinases, cellulases and proteases, as the most important virulence factors, as well as pathogenicity toward potato tuber, were compared between the strains P. brasiliense BL-2 and P. carotovorum BL-4 at 28 â„ƒ. The results showed that P. carotovorum had higher cell wall-degrading enzyme activities and brought more severe disease symptoms to potato tubers than P. brasiliense. Moreover, the pathogenicity of P. carotovorum and P. brasiliense increased with increasing temperature (20, 25, 28, 32 â„ƒ). The pathogenicity was more severe when P. carotovorum strain BL-4 was co-inoculated with P. brasiliense strain BL-2, especially when the former exhibited an advantage in bacterial number at the initial time. The results of this study provide new insight for understanding the pathogenicity caused by mixed infections with different species of Pectobacterium spp., and they may provide some guidance for controlling potato blackleg and soft rot.