Rectification is observed in a single n-ZnO/p ++-Si nanoheterojunction using ultra high vacuum compatible scanning tunneling microscope. The nanohetrojunctions have been grown using catalyst free vapor-solid growth of ZnO nanorods on p ++-Si substarte. A high rectification ratio ∼100 at 2 V is observed in the current voltage measurements. Temperature dependent study in these nanoheterojunctions showed activation energy for carrier conduction ∼66 meV, which is primarily associated to the presence of heterojunction induced interface states. Role of ultra violet excitation on these finite sized (∼500 nm) nanoheterojunction is also studied with photo-generated electron-hole pairs. A Zener breakdown is observed in this photo-excitation process. Increase in the concentration of minority carriers and corresponding decrease in barrier width and height at the junction have been identified for the observed tunneling behavior under UV illumination. The large carrier concentration in the finite sized device with large diffusion length of electron (∼2 μm) is made responsible for the observed voltage regulation.
All Science Journal Classification (ASJC) codes
- Biomedical Engineering
- Materials Science(all)
- Condensed Matter Physics