THEORETICAL STUDY OF ADVANCED FIELD-EFFECT TRANSISTORS BASED ON ALTERNATIVE CHANNEL MATERIALS FOR SUPPLY VOLTAGE REDUCTION

Abstract

Power consumption has become a serious problem in highly-scaled transistors used in complementary-metal-oxide-semiconductor technology. Power consumption can be reduced by down-scaling the power supply voltage (VDD). In this thesis, metal-oxide-semiconductor field-effect transistors (MOSFETs) based on channel materials with high carrier velocity and density of states and tunneling field-effect transistor (TFET) are studied to enable the reduction of VDD. Band structures of alternative channel materials considered were obtained via empirical pseudopotential method, ab-initio, and tight-binding method. Their ballistic ON-current was computed using semiclasical transport model. Theoretical study of GeSn alloy reveals that GeSn n-MOSFET offers higher ON-current than Ge. Among channel materials studied for double-gate ultra-thin body MOSFET, Ge and GaSb transistors show good voltage scalability for High Performance application while silicon, black phosphorus, and silicane transistors showcase good voltage scalability for Low Power application. TFET with extended source was proposed for achieving higher ON-current and lower subthreshold swing.