banner8 banner8_m

News and Events

PAST EVENTS

BACK
Seminars

GaN/ZnO Heterojunction LEDs

Speaker Dr. A.B. Djurišić
Affiliation Department of Physics, The University of Hong Kong, HKU
Date December 15, 2009 (Tue)
Time 5:00 -6:00 p.m.
Venue Lecture Theatre P4, LG1/F, Chong Yuet Ming Physics Building, HKU

Abstract:

The direct wide band gap semiconductor ZnO has large exciton binding energy (60 meV) and its wurtzite crystal structure closely matches that of GaN, which is a conventional LED semiconductor. In addition, ZnO is chemically stable, non-toxic, low cost, and relatively abundant and it can be grown by simple, inexpensive methods such as electrodeposition. Due to the low lattice mismatch, p-GaN/n-ZnO heterojunction devices are of great interest. Also, LEDs based on 1D nanostructure are expected to give better device performance. Therefore, our work has been focused on p-GaN/n-ZnO nanorods based heterojunction. A variety of emission colors depending on the preparation parameters has been obtained, including devices with tunable emission from orange at 2.1 V over white at 2.5 V to blue at 2.7 V. Light extraction enhancement by random texturing using electrodeposited ZnO nanorods was also achieved. P-GaN/ZnO heterojunction devices with light extraction layer show an increase of 30-50% in emission intensity.

 

Coffee and tea will be served 20 minutes prior to the seminar.