While benefiting greatly from electronics, our society also faces a major problem of electronic waste, which has already caused environmental pollution and adverse human health effects. Therefore, recyclability becomes a must-have feature in future electronics. Here, we demonstrate an erasable and recreatable two-dimensional electron gas (2DEG), which can be easily created and patterned by depositing a water-dissolvable overlayer of amorphous Sr3Al2O6 (
a-SAO) on SrTiO3 (STO) at room temperature. The 2DEG can be repeatedly erased or recreated by depositing the a-SAO or dissolving in water, respectively. Photoluminescence results show that the 2DEG arises from the a-SAO–induced oxygen vacancy. Furthermore, by gradually depleting the 2DEG, a transition of nonlinear to linear Hall effect is observed, demonstrating an unexpected interfacial band structure. The convenience and repeatability in the creation of the water-dissolvable 2DEG with rich physics could potentially contribute to the exploration of next generation electronics, such as environment-friendly or water-soluble electronics.