Time Domain Thermoreflectance

Time Domain Thermoreflectance


Time Domain Thermoreflectance (TDTR) is a photothermal technique capable of measuring thermal conductivity of thin films and bulk substrates as well as thermal boundary resistance. This technique employs an ultrafast (pulse duration < 1 ps) laser in a pump (heating) probe (temperature sensing) configuration. The pump pulse is modulated between 1 and 12 MHz to control the thermal penetration depth and to use a lock-in amplifier to extract the signal. The probe pulse is sent through a mechanical stage to delay its arrival between 0.1 to 7 ns compared with the pump pulse to allow the temperature decay of the surface to be measured through this time frame. The temperature decay of the sample surface is related to a radial 2D multi-layer heat conduction model that allows the determination of various thermophysical properties. The temperature is measured through changes in reflectivity of a thin metal film (50-100 nm) deposited on top of the sample. Because the reflectivity of the surface is measured the sample must be smooth enough for a specular reflection. The system is capable of measuring thermal conductivity between 0.1 and 1000 W/m-K and thermal boundary resistance between 2 and 500 m2-K/GW.



Thermal Boundary Resistance in GaN Films Measured by Time Domain Thermoreflectance with Robust Monte Carlo Uncertainty Estimation

Thermal Conductance of Poly(3-methylthiophene) Brushes

Characterization of Carbon Nanotube Forest Interfaces Using Time Domain Thermoreflectance

Characterization of the Thermal Conductivity of CVD Diamond for GaN-on-Diamond Devices