Violet Arsenic Phosphorus: Switching p-Type into High Performance n-Type Semiconductor by Arsenic Substitution

Abstract

Violet phosphorus, a recently explored layered elemental semiconductor, has attracted much attention due to its unique photo-electric, mechanical properties, and high hole mobility. Herein, violet arsenic phosphorus has for the first time been synthesized by a molten lead method. The crystal structure of violet arsenic phosphorus (P83.4As0.6, CSD-2408761) was determined by single crystal X-ray diffraction to have similar structure as that of violet phosphorus, where P12 is occupied by arsenic/phosphorus (As/P) atoms as mixed occupancy sites As1/P12. The arsenic substitution has been demonstrated to tune the band structure of violet phosphorus, switching p-type of violet phosphorus to high-performance n-type violet arsenic phosphorus. The effective electron mass along the <010> direction is significantly reduced from 1.792 to 0.515 m0 by arsenic substitution, resulting in an extremely high electron mobility of 2622.503 cm2 V⁻1 s⁻1. The field effect transistor built with P83.4As0.6 nanosheets was measured to have a high electron mobility (137.06 cm2 V⁻1 s⁻1, 61.2 nm), even under ambient conditions for 5 h, much higher than the hole mobility of violet phosphorene nanosheets (4.07 cm2 V⁻1 s⁻1, 73.3 nm). This work provides a new idea for designing phosphorus-based materials for field effect transistors, giving significant potential in complementary metal–oxide–semiconductor applications.

1. Introduction

Violet phosphorus (VP) [1], the most stable allotrope of phosphorus, exhibits remarkable performances in anisotropic [2, 3], mechanical [4], electrical [5, 6], optical [7, 8], and photocatalytic [9–12] properties. The effective mass of charge carriers in a semiconductor, which significantly influences their overall semiconductor performance [13, 14], can be modulated through precise alterations in the band structure, leading to substantial improvements in performance for a variety of applications [15–17]. Atomic substitution is a pivotal strategy for bandgap engineering and further modulating the effective mass of charge carriers, tuning the carrier charge mobility of semiconductors.

The atomic substitution strategy is widely applied in 2D transition metal dichalcogenides (TMDCs) modification, which involves both the substitution of cationic part or anionic part with highly controllability [18]. For example, the effective charge carrier masses of antimony sulfide (Sb2S3) were found to be reduced by bismuth substitution of antimony, leading to variations of band dispersion and further enhancing optical properties [19]. The electronic properties of MoS2 were modified by substituting molybdenum atoms with niobium, resulting in altered p-type conductivity [20]. The band gap and optical properties of WS2 were adjusted by substituting tungsten atoms with niobium, achieving a stable and controllable p-type transport behavior [21]. The bandgap of MoS2 was tuned through substituting of sulfur with selenium using selenization [22]. Furthermore, the atomic substitution strategy has also been demonstrated to have potential to modify elemental phosphorus semiconductors. The band gap of black phosphorus (BP) was adjusted from 0.3 to 0.15 eV through the substitution of phosphorus with arsenic, leading to enhancements in its electronic and optical properties [23]. Significant improvements in both environmental stability and hole mobility were also observed in tellurium-substituted BP [24]. However, it is difficult to achieve a controllable atomic substitution of a phosphorus allotrope while maintaining its pristine crystal structure. Nevertheless, it is always a big challenge to grow high-quality single crystals in order to determine their accurate crystal structures.

The accurate crystal structure of semiconductors is crucial for precisely understanding and optimizing material properties [25]. The crystal structure of black phosphorus was determined by single-crystal X-ray diffraction (SC-XRD) i