Methods of forming a settable resistance device, settable resistance devices, and neuromorphic computing devices include isotropically etching a stack of layers, the stack of layers having an insulator layer in contact with a conductor layer, to selectively form divots in exposed sidewalls of the conductor layer. The stack of layers is isotropically etched to selectively form divots in exposed sidewalls of the insulator layer, thereby forming a tip at an interface between the insulator layer and the conductor layer. A dielectric layer is formed over the stack of layers to cover the tip. An electrode is formed over the dielectric layer, such that the dielectric layer is between the electrode and the tip.