A semiconductor device such as a P-N or P-I-N junction diode, includes a first semiconductor layer having a first conductivity-type and being mounted over a metal address line, and a second semiconductor layer having a second conductivity-type and being mounted over the first semiconductor material. The diode preferably has a thickness of substantially no more than about 1 micron, and the diode includes a P-N junction confined to a thickness of less than about 0.1 micron. In the preferred embodiment the method comprises depositing a first semiconductor layer having a first conductivity type, depositing a second intrinsic layer, annealing to convert both layers to a polycrystalline layer, implanting ions of a second conductivity type into the second layer, and annealing to convert the second layer to a polycrystalline. The result is a diode having an ultra-sharp p-n junction.