TOPIC (1) :

Enhanced Light Extraction from GaN-based Light Emitting Diodes with ZnO Nanorods grown on ITO-based p-type Ohmic Contact

SPEAKER (1)

Mr. Dai Kehui,  (NUS  Non-exchanged student ), COE, ECE, NUS

TIME (1) :

2.00 pm  to  2.40 pm

ABSTRACT (1) :

Enhancement of light extraction from GaN-based light emitting diodes (LEDs) with ZnO nanorods has been demonstrated. ITO-based transparent conductive layer was first deposited on top of GaN-based LEDs and used as a p-type ohmic contact and an optically transparent window for the light emission. ZnO nanorods were hydro thermally grown on ITO surface, on which ZnO nanoparticle seeds were previously prepared.

The light extraction of the light emitting diodes with ZnO nanorods exhibited an enhancement in EL intensity, compared with that of the light emitting diodes without ZnO nanorods will be discussed. The improved emission efficiency of the LEDs which attributed by the enhanced light transmission and scattering of ZnO nanorods will also be presented in this seminar.

BIOGRAPHY (1)

Mr. Dai Kehui received his B.Sc degree from Department of Optoelectronic Science and Engineering, Huazhong University of Science and Technology in China in 2005. Currently, he is a PhD student of Huazhong University of Science and Technology and studying in NUS as a Non-exchanged student. His research interest is focused on ohmic contact on p-type GaN and light extraction efficiency improvement for GaN-based light emitting diodes.

TOPIC (2) :

Dislocation reduction during Ge growth on Si by Epitaxial Necking

SPEAKER (2)

Mr. Zhang Liang (PhD student), SMA-COE, ECE, NUS

TIME (2):

2.50 pm  to  3.40 pm

ABSTRACT (2) :

Lattice-mismatched heteroepitaxial semiconductors are of great interest for a number of applications in electronics and optoelectronics. A high-quality Ge epilayer on Si may serve as a buffer to integrate III-V photonic and high-mobility electronic devices with Si-based integrated circuits. The main barrier to the epitaxial growth of Ge and III–V films on Si is the misfit dislocations formed at the substrate/film interface due to the lattice mismatch between these materials and Si. In this seminar, we will discuss the mechanism of dislocation formation and movement during GeSi growth as well as other defects, then introducing the epitaxial necking technique to reduce dislocation and our recent new development based on this technique will be presented.

BIOGRAPHY (2)

Mr. Zhang Liang obtained his Bachelor degree in Physics and Master degree in Optics from Wuhan University, China, at 2006. He joined Singapore-MIT Alliance as a PhD candidate in the year 2006.His research topic is on novel photonic device based on Si platform.