(Raw Data Set) Two-dimensional P3m1 Ca3N2, Ba3P2, and Ba3As2: Promising stable narrow-gap semiconductors for infrared and broadband photodetectors

Abstract

Exploring two-dimensional (2D) narrow-gap materials with exceptional stability and outstanding photoelectric performance has become a key focus in nano-optoelectronics. However, most existing 2D materials contain relatively large band gaps, and those with narrow band gaps tend to have inadequate stability. This study employed first-principles calculation to predict three alternative narrow-gap 2D binary group (II3-V2) materials in the P3m1 space group: Ca3N2, Ba3P2, and Ba3As2. All these materials exhibit excellent energetic, mechanical, dynamic, and thermal stability. Their mechanical properties reveal isotropic characteristics and demonstrate excellent in-plane stiffness and flexibility. Regarding electronic properties, monolayer Ca3N2, Ba3P2, and Ba3As2 possess indirect narrow band gaps of 0.41, 0.61, and 0.68 eV, respectively. Moreover, they exhibit high electron mobilities (about 103-104 cm2 V-1 s-1) and are nearly isotropic. In terms of optical properties, they demonstrate a significantly broad absorption range, spanning from the IR to visible and UV regions, with remarkably high absorption coefficients (approximately 104-105 cm-1). Additionally, their exciton binding energies are higher than those observed in traditional bulk materials while lower than most other 2D materials, facilitating excellent light-driven performance. We propose that these alternative 2D P semiconductors will hold promising application prospects in nano-optoelectronic fields such as IR light detection, ambipolar transistors, medical imaging, electrodes, optical communication, and remote sensing. 3m1 Ca3N2, Ba3P2, and Ba3As2 binary narrow-gap