Erratum: “Note: Multi-gap gas switch with low trigger-threshold voltage by mounting resistors and capacitors in parallel with switch gaps” [Rev. Sci. Instrum. 89, 096105 (2018)]

Three-dimensional anisotropic thermal conductivity tensor of single crystalline β-Ga2O3

“…In this work, the 3D anisotropic thermal conductivity tensor of a β-Ga2O3 single crystal is measured using a recently developed elliptical-beam TDTR method. 13 By using a highly elliptical pump beam for heating the sample in TDTR experiments, the detected signals are selectively sensitive to the in-plane thermal conductivity along the short axis of the elliptical beam and the through-plane thermal conductivity but in different manners. 13 The 3D anisotropic thermal conductivity tensor of the sample can thus be derived from a series of measurements by rotating the elliptical pump beam.…”

“…13 By using a highly elliptical pump beam for heating the sample in TDTR experiments, the detected signals are selectively sensitive to the in-plane thermal conductivity along the short axis of the elliptical beam and the through-plane thermal conductivity but in different manners. 13 The 3D anisotropic thermal conductivity tensor of the sample can thus be derived from a series of measurements by rotating the elliptical pump beam. Our results suggest that at room temperature the highest in-plane thermal conductivity is along a direction between [001] and [102], with a value of 13.3±1.8 W m -1 K -1 , and the lowest in-plane thermal conductivity is close to the [100] direction, with a value of 9.5±1.8 W m -1 K -1 .…”

“…Details of the elliptical-beam TDTR method and the TDTR system for thermal conductivity tensor measurements were described elsewhere. 13,17 To conduct the elliptical-beam TDTR measurements, a pair of cylindrical lenses were inserted in the pump path to generate a highly elliptical pump spot on the sample surface, whereas a circular beam was still used as the probe. To characterize the spot size, the pump spot was swept across the probe spot at a high modulation frequency of 10 MHz and a short positive delay time of 100 ps.…”

“…Thermal properties of the sample, including the in-plane thermal conductivity in the θ angle K||(θ), the through-plane thermal conductivity Kz, and the Al/Ga2O3 interface thermal conductance G, were determined by fitting the measured ratio signals / as a function of delay time using a thermal transport model. 13 Figure 1…”

Tutorial: Time-domain thermoreflectance (TDTR) for thermal property characterization of bulk and thin film materials

“…While TDTR signals are most sensitive to thermal conductivity in the through-plane direction, TDTR can also be configured to measure anisotropic thermal transport properties. Several advanced approaches based on TDTR have been developed, including a variable spot size configuration, 37 a beam-offset configuration, 86,87 and an elliptical-beam configuration, 119 all with their own advantages. A summary and comparison of the three different configurations are presented in Table 1, with the details discussed below.…”