• Violet arsenic phosphorus (VP-As) single crystals were synthesized and characterized by single crystal X-ray diffraction to be P83.4As0.6 (CSD-2408761), with P12 occupied by arsenic/phosphorus as a mixed occupancy site.
• The p-type VP has been switched into n-type VP-As, significantly reducing the effective electron mass and resulting in high electron mobility of 2622.503 cm2 V−1 s−1.
• Field effect transistors built with P83.4As0.6 nanosheets achieved a high electron mobility of 137.06 cm2 V−1 s−1, much higher than the hole mobility of VP.
• This work provides a new strategy for designing phosphorus-based materials for field effect transistors, with significant potential in complementary metal–oxide–semiconductor applications.