Half semiconductors, capable of achieving 100% spin-polarized carriers under simple electrostatic gating, optical excitation, and thermal excitation conditions, have emerged as some of the most promising materials for spintronics. Thus, to find new half-semiconducting materials is highly desirable. Herein, we propose a two-dimensional half-semiconducting material, $\mathrm{Mn}{\left(\mathrm{BiTeS}\right)}_2$, and its various physical properties and potential applications are predicted. The energetic, dynamic, thermal, and mechanic stability is highly identified by variously related calculations, implying that $\mathrm{Mn}{\left(\mathrm{BiTeS}\right)}_2$ possibly exists in experiment. It holds a high magnetic anisotropy energy in the ferromagnetic ground state, with Curie temperature up to 54.3 K. It also possesses outstanding mechanical and optical properties as well as high carrier mobility. Besides, multiple kinds of sub-3 nm functional device prototypes are designed and their excellent transport behaviors are revealed. For example, the $pn$-junction diode exhibits a high spin filtering and strong rectification effect. While rectification for $A$-type pin-junction field-effect transistor is more advantageous, with rectification ratio reaching ${10}^{11}$. Besides, the nin-junction and pip-junction field-effect transistors manifest an intriguing negative differential resistance phenomenon. The pip-junction field-effect transistor can achieves 100% spin filtering, and the pin-junction phototransistor exhibits excellent optical response and can distinguish colors based on the spin-dependent photocurrents.

• Received 1 August 2023
• Revised 7 October 2023
• Accepted 3 November 2023

DOI:https://doi.org/10.1103/PhysRevB.108.184413