An apparatus and a method of manufacturing the apparatus. The apparatus includes a main nanowire and branch nanowires emanating from the main nanowire. The main nanowire may have a first portion and a second portion. The first portion may have a first carrier concentration and the second portion may have a second carrier concentration, different to the first carrier concentration. Each branch nanowire may emanate from the first portion of the main nanowire. Each branch nanowire may emanate from the main nanowire at a substantially fixed distance along a length of the main nanowire.