A device comprising one or more field effect transistors, each field effect transistor comprising: an elongated drain contact line comprising an electrically conductive material extending along a first horizontal direction; a drain comprising a first conductivity type semiconductor region overlaying the drain contact line; a source comprising a the first conductivity type semiconductor region located above the drain; a gate extending vertically between the drain and the source, wherein: the gate is elongated along a second horizontal direction transverse to the first horizontal direction; the gate comprises a first vertical side and an opposing second vertical side, each vertical side contacting a gate insulating material; the gate comprises a top portion adjacent to the source and electrically insulated from the source by a gate top isolation layer of insulating material; and the gate comprises a bottom portion adjacent to the drain and electrically insulated from the drain by a gate bottom isolation layer of insulating material; and characterised in that it further comprises a first channel and a second channel, each comprising a second conductivity type semiconductor region different from the first conductivity type, wherein: the first channel extends vertically from the drain to the source and is located on the first vertical side of the gate and is electrically insulated from the gate by the gate insulating material contacting the first vertical side of the gate; and the second channel extends vertically from the drain to the source and is located on the second vertical side of the gate and is electrically insulated from the gate by the gate insulating material contacting the second vertical side of the gate. an elongated drain contact line comprising an electrically conductive material extending along a first horizontal direction; a drain comprising a first conductivity type semiconductor region overlaying the drain contact line; a source comprising a the first conductivity type semiconductor region located above the drain; a gate extending vertically between the drain and the source, wherein: the gate is elongated along a second horizontal direction transverse to the first horizontal direction; the gate comprises a first vertical side and an opposing second vertical side, each vertical side contacting a gate insulating material; the gate comprises a top portion adjacent to the source and electrically insulated from the source by a gate top isolation layer of insulating material; and the gate comprises a bottom portion adjacent to the drain and electrically insulated from the drain by a gate bottom isolation layer of insulating material; and characterised in that it further comprises a first channel and a second channel, each comprising a second conductivity type semiconductor region different from the first conductivity type, the gate is elongated along a second horizontal direction transverse to the first horizontal direction; the gate comprises a first vertical side and an opposing second vertical side, each vertical side contacting a gate insulating material; the gate comprises a top portion adjacent to the source and electrically insulated from the source by a gate top isolation layer of insulating material; and the gate comprises a bottom portion adjacent to the drain and electrically insulated from the drain by a gate bottom isolation layer of insulating material; and characterised in that it further comprises a first channel and a second channel, each comprising a second conductivity type semiconductor region different from the first conductivity type, wherein: the first channel extends vertically from the drain to the source and is located on the first vertical side of the gate and is electrically insulated from the gate by the gate insulating material contacting the first vertical side of the gate; and the second channel extends vertically from the drain to the source and is located on the second vertical side of the gate and is electrically insulated from the gate by the gate insulating material contacting the second vertical side of the gate. the first channel extends vertically from the drain to the source and is located on the first vertical side of the gate and is electrically insulated from the gate by the gate insulating material contacting the first vertical side of the gate; and the second channel extends vertically from the drain to the source and is located on the second vertical side of the gate and is electrically insulated from the gate by the gate insulating material contacting the second vertical side of the gate.