Contact Resistance in Semiconductor Devices

This lecture covers the concept of contact resistance in semiconductor devices, discussing its practical implications, measurement techniques such as the 4-probe and TLM methods, and the impact of contact geometry on resistance scaling. It also explores quantum resistance in ballistic conductors, quantized conductance in materials like GaAs, graphene, and MoS₂, and the challenges of spin injection due to conductivity mismatch. Additionally, it examines the band alignment in heterostructures, valley polarization by spin injection, and strategies for reducing contact resistance through phase engineering, doping, and contact transfer.