Optical and Electrical Characteristics of n-ZnSmO/p-Si Heterojunction Diodes

Sm doped ZnO nanoparticles were synthesized by a simple wet chemical route. The obtained nanomaterials were studied for their structural, morphological and optical properties. The average crystalline size of the ZnO nanomaterials were enhanced from 50 nm to 70 nm for the Sm doping concentration. The morphological properties were elucidated with the aid of SEM images, in which the ZnO nanoparticle size of about 60-100 nm were enhanced to micron size for Sm dopants. The optical absorbance spectrum indicated the enhanced photons absorption of the nanoparticles in both UV and visible region with red shift in the characteristic excitonic absorption band edge. The band gap of ZnO nanoparticles (3.31 eV) had narrowed to 2.84 eV for the doping of Sm3+ ions in the lattices of Zn-O, since the charge transformation between the 4f electronic level of Sm3+ ions and conduction band of ZnO. The obtained pn junction structures (n-ZnSmO/p-Si) have also showed the enhanced electrical conductivity for ZnSmO specimens, due to the contribution 4f rich electrons of Sm3+ ions. Further the various device parameters were calculated and their interpretations with the material properties were also discussed in detail.