The paper by S. Heinze, J. Tersoff, R. Martel, V. Derycke, J. Appenzeller, and Ph. Avouris from IBM Research Division explores the operation of carbon nanotube (CNT) transistors as unconventional "Schottky barrier transistors" (SB-FETs). The authors demonstrate that transistor action in CNT-FETs primarily occurs through variations in contact resistance rather than channel conductance. They calculate the characteristics of these devices for both idealized and realistic geometries and show that scaling behavior is evident. The study explains various experimental observations, including the effects of doping and adsorbed gases, and highlights the crucial role of electrode geometry in device performance. The results suggest that tailoring the contact geometry can significantly improve device performance, particularly by focusing the electric field at the contact. The paper also discusses the different behaviors observed when the metal Fermi level falls in the middle or off-center of the CNT bandgap, leading to asymmetric or symmetric conductance curves. Additionally, the authors argue that changes in workfunction due to adsorbed gases primarily affect the Schottky barrier rather than doping the CNTs.The paper by S. Heinze, J. Tersoff, R. Martel, V. Derycke, J. Appenzeller, and Ph. Avouris from IBM Research Division explores the operation of carbon nanotube (CNT) transistors as unconventional "Schottky barrier transistors" (SB-FETs). The authors demonstrate that transistor action in CNT-FETs primarily occurs through variations in contact resistance rather than channel conductance. They calculate the characteristics of these devices for both idealized and realistic geometries and show that scaling behavior is evident. The study explains various experimental observations, including the effects of doping and adsorbed gases, and highlights the crucial role of electrode geometry in device performance. The results suggest that tailoring the contact geometry can significantly improve device performance, particularly by focusing the electric field at the contact. The paper also discusses the different behaviors observed when the metal Fermi level falls in the middle or off-center of the CNT bandgap, leading to asymmetric or symmetric conductance curves. Additionally, the authors argue that changes in workfunction due to adsorbed gases primarily affect the Schottky barrier rather than doping the CNTs.