ON Semiconductor, BSS123LT1G, Transistors, Mosfets

 The metal–oxide–semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET), also known as the metal–oxide–silicon transistor

https://www.futureelectronics.com/p/semiconductors--discretes--transistors--mosfets/bss123lt1g-on-semiconductor-9076993