Memory devices, methods for fabricating, and methods for adjusting flatband voltages are disclosed. In one such memory device, a pair of source/drain regions are formed in a semiconductor. A dielectric material is formed on the semiconductor between the pair of source/drain regions. A control gate is formed on the dielectric material. A charged species is introduced into the dielectric material. The charged species, e.g., mobile ions, has an energy barrier in a range of greater than about 0.5 eV to about 3.0 eV. A flatband voltage of the memory device can be adjusted by moving the charged species to different levels within the dielectric material, thus programming different states into the device.