A select device may have its threshold current reduced relative to the threshold current of a phase change memory element by providing within the select device a breakdown layer. Because the breakdown layer forms a breakdown filament along its length, the relative area between layers may be reduced, reducing the threshold current of the select device relative to that of the memory element. In addition, a stack may be formed with the select device over the memory element. The select device may be arranged so that the position of the breakdown filament may be moved inwardly relative to the etched edge to also reduce leakage current. In one embodiment, sidewall spacers may be formed on a portion of the select device.