Nanostructured n-ZnO / thin film p-silicon heterojunction light-emitting diodes

Electroluminescence (EL) was obtained from a p-Si (100) thin film/nanostructured n-ZnO heterojunction diode fabricated by a simple dielectrophoresis (DEP) method. The Si substrate was pre-patterned with electrodes and an insulating separation layer by a standard photolithographic process. ZnO nanostructures were formed by a simple solution chemistry and subsequently transferred to the pre-patterned substrate. Application of the DEP force at a frequency of 100 kHz and 6 V peak-to-peak voltage allowed precise positioning of the ZnO nanostructures at the edge of the metal electrodes. The physically formed p-Si (100) thin film/nanostructured n-ZnO heterojunction displayed multi-color emission from the ZnO near band edge as well as emission from defective states within the ZnO band gap.