The disclosed technology relates generally to semiconductor memory devices, and more particularly to three-dimensional (3D) ferroelectric memory devices, methods of fabricating 3D ferroelectric memory devices, and methods of conditioning 3D ferroelectric memory devices. The 3D ferroelectric memory device exploits programmed memory cells as selector devices. In one aspect, a 3D ferroelectric memory device comprises a stack comprising a plurality of gate electrode layers and spacer layers, which are alternatingly arranged. The 3D ferroelectric memory device additionally comprises a semiconductor channel extending through the stack and a ferroelectric layer arranged between the gate electrode layers and the semiconductor channel. The gate electrode layers form, in combination with the channel and the ferroelectric layer, a string of ferroelectric transistors, wherein each ferroelectric transistor is associated with one cell of the memory device. The first ferroelectric transistor and the last ferroelectric transistor in the string have a lower threshold voltage than the other ferroelectric transistors.