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.