Systematic investigations on doping dependent thermal transport properties of single crystal silicon by time-domain thermoreflectance measurements

Doped silicon (Si) is the key material in semiconductor industries. It is important to fully understand the doping effect on thermal transport properties of single-crystal Si, especially for the thermal management of Si-based electronic devices. In this work, we used a femtosecond-laser time-domain thermoreflectance method to characterize the thermal transport properties of Si with different doping concentrations (1013-1019 cm-3) and doping elements, boron (B) and phosphorus (P). Results show that the thermal conductivity of heavy doped Si (about 2 x 1019 cm-3) by both B and P decreases by about 22% compared with their pure counterparts. Theoretical calculations based on the Boltzmann transport equation were also carried out for comparison with measurement results, and different scattering terms were discussed to find out the main factors for suppressing the thermal transport in doped Si within different doping concentration ranges. Combining with a cryogenic system, the thermal conductivity of doped Si samples and interfacial thermal conductance between Si and aluminum thin films were also measured under low-temperature conditions (down to 160 K). Our systematic studies on the doping effect in the thermal transport of single-crystal semiconductors not only facilitate the understanding of the microscale thermal transport, but also provide references in industrial applications of doped semiconductors.

Automated summary

This study investigated the thermal transport properties of doped silicon using a femtosecond-laser time-domain thermoreflectance method. The results showed that heavily doped silicon had a 22% decrease in thermal conductivity compared to pure silicon. Theoretical calculations and measurements were used to analyze the factors affecting thermal transport in doped silicon. Additionally, measurements were conducted at low temperatures to determine the thermal conductivity of doped silicon samples and the interfacial thermal conductance between silicon and aluminum thin films. These systematic studies provide insights into microscale thermal transport and have implications for industrial applications of doped semiconductors.