Embodiments are directed to two-dimensional electron gas (2DEG)-confined 2DEG devices and methods. One such device includes a substrate and a heterostructure on the substrate. The heterostructure includes a first semiconductor layer, a second semiconductor layer, and a 2DEG layer between the first and second semiconductor layers. The device further includes a 2DEG device having a conduction channel in the 2DEG layer. An isolation electrode overlies the heterostructure and at least partially surrounds a periphery of the 2DEG device. The isolation electrode, in use, interrupts the 2DEG layer in response to an applied voltage.