Germanium is a promising semiconductor material for both electronic and photonic devices owing to its high carrier mobility and pseudo-direct-bandgap properties. Recently, several approaches have been explored to modulate the energy band structure of Ge to direct bandgap, such as introducing tensile strain and Sn alloying. Highly n-type doping was also proven to enhance direct bandgap emission from the Ga-based materials. Moreover, Ge(GeSn)-on-insulator structures have attracted great interest to realize the monolithic integration of Ge-based optoelectronic devices. Although various methods, including solid-phase crystallization and wafer bonding, have been studied to form GOI and GeSnOI structures, these methods have difficulties achieving high-quality Ge and GeSn layers. In this study, we fabricated tensile-trained single-crystalline local GOI and GeSnOI structures by lateral liquid-phase epitaxy (LLPE), in which amorphous Ge and GeSn wires surrounded by SiO₂ layers but partly connected to the Si seed regions were melted to induce lateral growth in the micro-crucibles. Biaxial tensile strain (0.3 – 0.4%) was spontaneously induced by the large difference in the thermal expansion coefficients between Ge(GeSn) wires and Si substrates. Moreover, whereas n-type doping of Ge-based materials is generally difficult because of the high diffusivity and low solid solubility of dopant atoms, highly n-type doping can be achieved in the LLPE method by incorporating Sb atoms into the initial amorphous Ge and GeSn layers. Our micro-photoluminescence spectroscopy study revealed that direct gap emission was enhanced more than 30 times than that of reference Ge substrates at room temperature and that the emission intensity increased with the decrease in measurement temperature, indicating a significant increase in electron density at the Brillouin zone center due to high Sb doping. Moreover, Fabry-Pérot resonator made of the highly doped Ge and GeSn wires showed clear resonance peaks even at room temperature.