For the mechanical stability of heterostructure membranes such as LaAlO₃ (LAO)/SrTiO₃ (STO), which is well-known for two-dimensional electron transport at the interface, a thick template substrate layer is required. However, thick STO films typically suffer from the formation of undesired point defects, mainly due to its cation off-stoichiometry, which results in the insulating interface with LAO. Herein, we report the successful fabrication of a conducting interface between LAO and thick homoepitaxial STO films by pulsed laser deposition. The careful optimization of laser ablation parameters including laser energy density and laser spot size led to stoichiometric 500 nm–thick STO films that have a lattice structure identical to that of bulk single crystals of STO, as confirmed by X-ray diffraction and temperature-dependent Raman spectroscopy. The interface between 4 nm–thick LAO and 500 nm–thick stoichiometric STO films exhibited a metallic behavior at low temperature down to 4 K, implying a low concentration of point defects in the homoepitaxial STO film. Ultimately, a crack-free, millimeter-sized 500 nm–thick STO membrane was successfully fabricated. These results are expected to facilitate the integration of high-quality complex oxide heterostructure membranes with various substrates including silicon, enabling their practical applications.

用于异质结构膜的机械稳定性，例如 LaAlO ₃ (LAO)/SrTiO ₃（STO），它以界面处的二维电子传输而闻名，因此需要厚的模板衬底层。然而，厚 STO 薄膜通常会形成不希望的点缺陷，这主要是由于其阳离子偏离化学计量，导致与 LAO 的绝缘界面。在这里，我们报告了通过脉冲激光沉积成功制造了 LAO 和厚同质外延 STO 薄膜之间的导电界面。激光烧蚀参数（包括激光能量密度和激光光斑尺寸）的仔细优化导致化学计量 500 nm 厚的 STO 薄膜具有与 STO 体单晶相同的晶格结构，这已通过 X 射线衍射和温度依赖性得到证实拉曼光谱。4 nm 厚的 LAO 和 500 nm 厚的化学计量 STO 薄膜之间的界面在低至 4 K 的低温下表现出金属行为，这意味着同质外延 STO 薄膜中的点缺陷浓度较低。最终，成功制造出无裂纹、毫米大小的 500 nm 厚 STO 膜。这些结果有望促进高质量复合氧化物异质结构膜与包括硅在内的各种基板的集成，从而实现其实际应用。