[en] Hemispherical p/n/p transistor structures ranging from 100 microns down to 0.05 microns are fabricated in CuInSe₂ by application of a high electric field between a conducting diamond tip of an Atomic force Microscope and a CuinSe₂ crystal. This leads to electromigration of Cu ions in the bulk of the material. The structures are characterized by nm scale scanning spreading resistance and scanning capacitance microscopy to reveal the inhomogeneous doping profile which was created by the electric field. For such transistor structures there is a lower limit in size which is roughly 10L (where L is the Debye length). The size of our smallest fabricated structure is close to this limit