Strain-tuned full spin polarization and ndoping of phosphorene via the phosphorene/Co[formula omitted]Sn[formula omitted]S[formula omitted] heterojunction

Abstract

Phosphorene’s desired bandgap, high carrier mobility and weak spin–orbit coupling qualify it as an exceptional semiconductor spin channel material. These traits underscore the importance of examining phosphorene’s electronic structure and that of half-metal heterojunctions (HJs) in innovating spintronic device design. This paper methodically investigates the electronic structure and Schottky barrier (SB) of a van der Waals HJ, comprising phosphorene and the half-metal Co3Sn3S2, subjected to biaxial mechanical strain via a first-principles method. The investigation unveils that phosphorene, as an n-type semiconductor, possesses substantial spin polarization. Remarkably, phosphorene undergoes three states – metallic, half-metallic, and semiconducting – subject to varying strain ratios (E). Furthermore, we discern that phosphorene’s spin polarization, peaking at 100% for −2%<E<1%, is tunable with strain. The SB heights (SBHs) also exhibit a consistent escalation with strain: for −5%≤E<1%, the electron SBH is 0 eV, which increments from 0.017 eV to 0.021 eV for 1%≤E≤3%. Intriguingly, the spin-down band alignment of the HJ transitions from type-II to type-I at E= 3%. Our Bader charge analysis validates that the n-doping of phosphorene is primarily due to electron acceptance from Co3Sn3S2. The orbital hybridizations between phosphorene and Co3Sn3S2 leads to complete spin polarization of phosphorene. Collectively, these observations confirm phosphorene’s capability to attain n-type doping with 100% spin polarization. Moreover, our findings suggest the possibility to modulate both the bandgap of phosphorene and the SBHs of the HJ with strain. This highlights the potential of the phosphorene/Co3Sn3S2 HJ in advancing the field of low-dimensional, flexible spintronics.