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Effects on structural characteristics of growth temperature and Si doping in GaN thin films grown on high temperature GaN were investigated. The GaN/GaN homojunction structure was grown via MOCVD at intermediate temperature (IT, 840 °C) with various Si doping concentrations. V-shaped pits are observed on the surface of the undoped GaN grown at IT by AFM morphology analysis. TEM two beam images show that only screw-and mixed-type components of dislocations contribute to pit formation. Moderate Si doping reduces the pit density, but over-doping of Si deteriorates the IT-GaN property by forming pits again. Not all pits are related with threading dislocations but some of them are observed in the dislocation free area of high Si-doped GaN.

Liquid metals (LMs) have gained great attention due to their fluidic behavior and metallic characteristics, suggesting the LMs to be an ideal electrode material for stretchable electronic textiles (e-textiles) in real-time healthcare systems. Despite advancements in material design techniques enabling LMs to monitor physiologic conditions on the skin, the low biostability of LMs remains challenging for practical use in e-textile. Here, we introduce a mechanically responsive and conductive gold nanoparticle (Au NP) layer as encapsulation on the LM layer to monitor healthcare systems with stretchable benefits. The Au NPencapsulated LM-based e-textile (AuLM textile) shows high electrical and mechanical stabilities under stretching deformation. We also demonstrate that Au NPs can maintain bonding to the fluidic LM layer when stretched and after stretching. The AuLM textile is equipped with biocompatibility and high electrochemical performance, resulting in multimodal biomedical applications. The electrochemical performance of the AuLM textile allows for sweat component detection and noninvasive, high sensitivity estimation of blood sugar contents. In addition, electrocardiography and electromyography measurements determined that the stretchable platform provides stable monitoring results under motion, and the Au NP encapsulation solves the biostability issue caused by a bare LM environment. This is the first demonstration of preparing stretchable e-textiles using the LM platform with practical and multimodal benefits. The study will open numerous design opportunities for next-generation stretchable bioelectronic applications.