Localized Charge Doping in Carbon Nanotube Field-Effect Transistors via Metal Subnanocluster Absorption

A semiconducting carbon nanotube (CNT) has been considered as a promising channel material for high-performance field-effect transistors (FETs) in the post-Moore era. The significant ungated resistance in the gate extension region reduces the maximum current (I_max) and limits the scaling process of CNTFETs. Here, we systematically report charge-doping strategies by designing metal subnanocluster absorption onto CNTs. When density functional theory simulations were combined with experimental synthesis and measurements, it was found that Pd subnanoclusters are well-suited for p-type doping and Sc and Y are more effective for n-type doping in CNTFETs. The former maintains an average saturated I_max of 1410 μA/μm and an average peak transconductance (g_m) of 597 μS/μm in 200-nm-L_ch CNTFET. Our work demonstrated the availability of using metal subnanoclusters for polarity-controlled localized doping in the gate extension region for short-channel CNTFETs or similar low-dimensional semiconductors.