Fabrication of voltage-gated spin Hall nano-oscillators. Issue 4 (12th January 2022)

• Record Type: Journal Article
• Authors: Kumar, Akash; Rajabali, Mona; González, Victor Hugo; Zahedinejad, Mohammad; Houshang, Afshin; Åkerman, Johan
• Is Part Of: Nanoscale. Volume 14:Issue 4(2022)
• Page Start: 1432
• Page End: 1439
• Publication Date: 2022-01-12
• Subjects: Nanoscience -- Periodicals; Nanotechnology -- Periodicals; 620.505
• DOI: 10.1039/d1nr07505e
• Languages: English
• ISSNs: 2040-3364

Abstract

Abstract : Schematic of nano-gate voltage controlled spin Hall nano-oscillator and significantly large frequency tunability with applied voltage and negligible leak current. Abstract : We demonstrate an optimized fabrication process for electric field (voltage gate) controlled nano-constriction spin Hall nano-oscillators (SHNOs), achieving feature sizes of <30 nm with easy to handle ma-N 2401 e-beam lithography negative tone resist. For the nanoscopic voltage gates, we utilize a two-step tilted ion beam etching approach and through-hole encapsulation using 30 nm HfO x . The optimized tilted etching process reduces sidewalls by 75% compared to no tilting. Moreover, the HfO x encapsulation avoids any sidewall shunting and improves gate breakdown. Our experimental results on W/CoFeB/MgO/SiO2 SHNOs show significant frequency tunability (6 MHz V −1 ) even for moderate perpendicular magnetic anisotropy. Circular patterns with diameter of 45 nm are achieved with an aspect ratio better than 0.85 for 80% of the population. The optimized fabrication process allows incorporating a large number of individual gates to interface to SHNO arrays for unconventional computing and densely packed spintronic neural networks.