Development of a rigid suspended micro-island device and robust measurement method for thermal transport measurements.

One of the most versatile techniques to study thermal transport in low dimensional materials utilizes a suspended micro-island device integrated with resistance thermometers. Advancements in experimental techniques with suspended micro-island devices resulted in increasing capabilities such as enhancing temperature resolution and expanding a measurable range of sample thermal conductance. In this work, we further improve the suspended micro-island based technique. Specifically, we present a rigid structure of the suspended micro-island device and robust measurement method for sequential heating. The rigid structure enabled by T-shaped beams prevents the displacement of suspended micro-islands, thus increasing the success rates of sample transfer especially for samples with a large cross-sectional area and short length. Besides, thermal isolation of micro-islands is maintained at a similar level through the T-shaped beams compared to conventional flat beams. Next, we introduce an advanced experimental approach that enables sequential heating to measure sample thermal conductance. Sequential heating in micro-islands can be used either to measure accurate sample thermal conductance even under unexpected asymmetric supporting beam configuration or to study thermal transport dependence on heat flow directions. Using a switch matrix for sequential heating eliminates the need for experimental reconfigurations during the experiment. We demonstrate the experimental method with thermal conductivity measurements of the Si nanowire under both the ideal symmetric beam configuration and replicated asymmetric beam configuration scenarios. The results show that the developed experimental method effectively eliminates potential experimental errors that can arise from the asymmetry in beam configurations.