Spreading resistance refers to the phenomenon in which current spreads through a material or device, resulting in a decrease in resistance. This is often seen in semiconductor materials, where the current is not confined to a specific path but can spread out across the material.
Spreading resistance is typically measured using a technique called spreading resistance profiling (SRP). This involves using a probe to apply a small voltage to the material and measuring the resulting current. By varying the position of the probe, a map of the resistance distribution across the material can be created.
The spreading resistance of a material can be influenced by several factors, including the material's composition, its doping level, and temperature. Additionally, the geometry and dimensions of the material can also play a role in determining its spreading resistance.
Spreading resistance measurements are commonly used in the semiconductor industry for materials characterization and quality control. They can also be used to map the electrical properties of different regions within a device, such as transistors or diodes. Additionally, spreading resistance can be used to study the effects of ion implantation and other fabrication processes on material properties.
Sheet resistance is a measure of the resistance per square of a material. It is related to spreading resistance in that as the current spreads out over a larger area, the sheet resistance decreases. In fact, spreading resistance measurements can be used to determine the sheet resistance of a material by measuring the resistance at different probe spacings and using mathematical models to calculate the sheet resistance value.