Past Events

Abstract:

The wide band gap semiconductor zinc oxide is of great interest for its potential uses in optoelectronic devices. Due to the difficulties in having a stable and reproducible p-type ZnO, ZnO based heterojunction devices are of more interest. In particular, 1-D nanostructure-based light emitting diodes (LEDs) are expected to have better performance compared to thin film devices. Therefore, this work concentrates on the investigation of ZnO nanorod based heterojunction LEDs with different p-type semiconductors.

We have studied ZnO nanorod based heterojunction LEDs with solution growth for both the n-ZnO and p-type material, i.e. chromium (VI) oxide (CrO₃). The effect of post-growth treatment (annealing under different conditions) on the device performance was investigated since the optical and electronic properties of ZnO are significantly affected by annealing.

P-GaN/n-ZnO nanorod heterojunction LEDs are also studied in this work. We have studied p-GaN/n-ZnO heterojunction for different GaN substrates and different growth methods for ZnO nanorods (electrodeposition and hydrothermal growth of different seed layers). The effect of annealing atmosphere and temperature on the device performance were also investigated since annealing has a significant effect on optical properties and the carrier concentration of ZnO nanorods. Finally, the fabrication of ZnO nanorod based LEDs on commercial GaN-based LED wafers without any etching was demonstrated.

We have also studied an organic/inorganic hybrid nanostructures based on 3,4,9,10-perylenetetracarboxylicdimide (PTCDI) and ZnO nanorods. PTCDI is an n-type organic material and we have demonstrated the growth of PTCDI nanoclusters on the ZnO nanorods surface. The effect of ZnO nanorods properties on the luminescence of the hybrid nanostructures was investigated.