Interface-engineered barium magnetoplumbite–wide-bandgap semiconductor integration enabling 5G system-on-wafer solutions for full-duplexing phased arrays

Abstract

Transition from fourth to fifth generation wireless technologies requires a shift from 2.3 GHz to Ka-band with the promise of revolutionary increases in data handling capacity and transfer rates at greatly reduced latency among other benefits. A key enabling technology is the integration of Ka-band massive multiple input–multiple output (m-MIMO) antenna arrays. m-MIMO array elements simultaneously transmit and receive (STAR) data providing true full duplexing in time and frequency domains. STAR requires, as a central component, the circulator. However, conventional circulators are bulky and prohibit the engineering of Ka array lattices. A necessary innovation calls for the integration of device-quality Ka-ferrites with wide-bandgap (WBG) semiconductor heterostructures allowing for system-on-wafer solutions. Here, we report results of a systematic study of pulsed laser deposited (PLD) barium magnetoplumbite (BaM) films on industrial compatible WBG semiconductor heterostructures suitable for operation in Ka-band circulators. We demonstrate successful PLD growth of BaM films on WBG semiconductor heterostructures. BaM films that show device quality performance in structure, epitaxy, and magnetic properties were realized for BaM/MgO/AlN/SiC(X). Film properties include bulk-like values of magnetic anisotropy field, Ha ∼16.5 kOe, and saturation magnetization, 4πMs ∼ 4.2 kG. Ferromagnetic resonance linewidth values are competitive and comparable with device design goals for insertion loss. Only heterostructures where SiC substrates have Si-polar surface showed superior properties. These results define a path for integration of magnetodielectric materials on wide bandgap heterostructures for self-biased devices essential to implementing millimeter-wave m-MIMO array and the enormous potential it offers to 5G technologies.

Review—Goodenough-Kanamori-Anderson Rules-Based Design of Modern Radio-Frequency Magnetoceramics for 5G Advanced Functionality

“…2 To this end, a central tenet of ongoing research is to demonstrate a viable path to the integration of ferrites with semiconductor platforms that are suitable for system-on-wafer (SoW) solutions that would enable Ka-band m-MIMO and ultimately the timely realization of 5G implementation. 4…”

“…In 2021, Yu et al, 4 demonstrated the growth by PLD of BaM/ MgO/AlN/SiC(X) heterostructures. The use of single crystal SiC substrates made this research more relevant for industrial applications.…”

Barium hexaferrites with narrow ferrimagnetic resonance linewidth tailored by site‐controlled Cu doping

“…With the soaring development of the electronics industry in the past few decades, M-type hexagonal ferrites, which possess a magnetoplumbite structure, have been attracting a lot of attention and research. [1][2][3][4][5][6][7][8][9][10][11] O 19 ), which are widely used in microwave devices, permanent magnets, and magnetic recording media due to their large magnetocrystalline anisotropy along the c-axis, high coercivity, and saturation magnetization. 1 Microwave circulators based on garnet or spinel ferrites usually need a bias field provided by an external magnetic steel to operate normally.…”

“…With the soaring development of the electronics industry in the past few decades, M‐type hexagonal ferrites, which possess a magnetoplumbite structure, have been attracting a lot of attention and research 1–11 . M‐type hexaferrites have two representative materials, barium hexaferrite (BaM, BaFe 12 O 19 ) and strontium hexaferrite (SrM, SrFe 12 O 19 ), which are widely used in microwave devices, permanent magnets, and magnetic recording media due to their large magnetocrystalline anisotropy along the c ‐axis, high coercivity, and saturation magnetization 1 .…”