Steady-State ThermoReflectance Fiberoptics

Steady-State ThermoReflectance Fiberoptics (SSTR-F) combines the technological power of laser based thermoreflectance experiments with the proven measurement capabilities of steady state thermal measurements. Utilizing small measurement volumes allows for rapid steady state measurements of materials with thermal conductivities ranging from as low as 0.05 Wm-1 K-1 up to 2,500 Wm-1 K-1. In addition to the wide range of accessible thermal conductivities, SSTR-F can accommodate sample sizes as small as a few hundred microns. Exploiting recent advances in fiber-optic components and laser systems allows for a safe, user-friendly tool capable of high throughput thermal conductivity measurements.

SSTR-F Specification

Materials Solids and Liquids
Thermal Conductivity Range 0.05 to 2500 W/m•K
Directional Measurement Through-thickness and In-plane
Spot Size Up to 100 microns
Temperature Range 80K – 600K
Accuracy 5%
Repeatability 2%
Thermal Conductivity Range 0.05 to 2500 W/m•K
Directional Measurement Through-thickness and In-plane
Thin-film Thickness > 5 nm

SSTR-F Applications

Bulk High Thermal Conductivity Small Samples

Bulk High Thermal Conductivity - Small Samples

Single Crystal silicon carbide (4H-SiC) wafer pieces of 2 mm diameter x 0.5 mm thickness were measured for thermal conductivity. SSTR-F testing results of 335 W/m·K +/- 28 W/m·K, correlated well with literature values (364 W/m·K) and traditional Time-domain Thermoreflectance (TDTR) measurements of 324 W/m·K.

High Thermal Conductivity Coatings

High Thermal Conductivity Coatings

High-purity aluminum nitride (AIN) coatings were grown on sapphire wafers at thickness of 6 μm. This coating was measured with test spot of 20 μm and 40 μm, and values were within +/- 5% of each other. The measured AIN in-plane thermal conductivity was measured at average of 283.7 W/m·K across multiple sample locations. Thermal conductivity values were observed to vary widely (+/- 36.3 W/m·K) due to micro-structure, grain size and defect concentrations. Additional measurement of bulk thermal conductivity on coatings as thin as 1 μm are also possible with SSTR-F.

High Resolution Thermal Mapping

Using the SSTR-F and automated X-Y movement testing stage, users are able to thermally map their samples for thermal conductivity. The testing spot size can be changed via varying objectives from 1 to 100 microns for sensitivity tuning, while the step size can be optimized to match the micro-structural length scales of a sample.

Sample Measurements

the sample


The Sample

Samples of interest and sapphire sample are coated with a thin metal layer and sapphire sample is tested to determine the gamma coefficient.

Approximate Time: 1 minute


Place Sample

Place sample on stage, specify number of tests, and specify spacing. Based on Z direction, the sample stage auto-focuses the laser.

Approximate Time: 1 minute


Run Experiment

The scan routine starts with autofocus at every point and runs user specified number of tests.

Approximate Time: < 2 minutes

export results


Export Results

Calculations of thermal conductivity with associated error are computed and reported.

Approximate Time: 1 minute

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