Co - Fe - B / Mg O / Ge Spin Photodiode Operating at Telecommunication Wavelength with Zero Applied Magnetic Field

• Published in: Physical review applied 2018-10, Vol.10 (4), Article 044049
• Main Authors: Djeffal, Abdelhak, Cadiz, Fabian, Stoffel, Mathieu, Lagarde, Delphine, Gao, Xue, Jaffrès, Henri, Devaux, Xavier, Migot, Sylvie, Marie, Xavier, Rinnert, Hervé, Mangin, Stéphane, George, Jean-Marie, Renucci, Pierre, Lu, Yuan
• Format: Article
• Language: English
• Subjects: Physics
• ISSN: 2331-7019; 2331-7019
• DOI: 10.1103/PhysRevApplied.10.044049

We report on the growth and study of Co-Fe-B/MgO/Ge(001) spin photodiode by using a combination of both molecular beam epitaxy (MBE) and sputtering methods. An epitaxial growth of MgO on Ge in MBE is achieved by the deposition of MgO at room temperature (RT) followed by a post-growth anneal-ing at 300 °C. The spin detector, which consists of 1.1-nm ultrathin Co-Fe-B layer capped with 5-nm Ta is subsequently grown by sputtering at RT. After a post-growth annealing of the whole structure at 250 °C, we obtain clear evidence of a strong perpendicular magnetic anisotropy in the temperature range 10-300 K. Co-Fe-B/MgO/Ge(001) heterojunctions are then processed into spin photodiodes demonstrating at zero magnetic field a photocurrent helicity asymmetry of about 0.9% at 9 K and 0.1% at RT at the telecommunication wavelength of 1310 nm. The demonstration of a spin photodiode working at a telecommunication wavelength with zero applied magnetic field is of great interest for future applications of the optical transport of spin information.