Semiconductor device including finFET and diode having reduced defects in depletion region

1. A semiconductor device, comprising:

a first substrate portion including a first active semiconductor layer defining at least one semiconductor fin and a first polycrystalline layer formed directly on the first active semiconductor layer, the first semiconductor layer defining at least one semiconductor gate; and

a second substrate portion separated from the first substrate portion by a predetermined distance, the second substrate portion including a doped region interposed between a second active semiconductor region and an oxide layer, the doped region including a first doped area and a second doped area separated by the first doped region to define a depletion region; and

a second polycrystalline material formed on an upper surface of the oxide layer to define a first ion implantation area adjacent a first side of the second polycrystalline material and a second ion implantation area adjacent a second side of the second polycrystalline material opposite the first side,

wherein the depletion region is integrally formed from the doped region, and wherein the first doped area, the second doped area and the depletion region define a diode.

2. The semiconductor device of claim 1 , wherein the oxide layer completely covers the second substrate portion.

3. The semiconductor device of claim 2 , wherein the first substrate portion excludes the oxide layer.

4. The semiconductor device of claim 1 , wherein the oxide layer has a thickness ranging from 15 nanometers to 30 nanometers.