Table 1.

The comparison of advantages and disadvantages of thermal technologies presented in the review to measure the in-plane k of films [68, 73, 74]

Methods	Advantages	Disadvantages	Sample geometry
Thermal bridge method	Substrate effect eliminated; can obtain k directly	The effect of thermal radiation losses and contact thermal resistance is ignored; extensive microfabrication works	Nanoscale or microscale samples
Flash method	Wide temperature range; fast and noncontact; low cost	Need surface coating; need smooth film surfaces; need specific heat capacity and density	> 100 µm in thickness
3ω method	Can obtain k directly; insensitive to the radiation and convective heat losses	Microfabrication of the metal stripe; need good insulation layer	Sub-micrometer thick samples
Steady-state infrared thermography	Fast and noncontact; can obtain k directly	Sample needs substantial optical absorptance and large emissivity; need extensive calibrations of the experimental set up	Sub-micrometer thick samples