Ultraviolet electroluminescence from n-ZnO-SiO2-ZnO nanocomposite/p-GaN heterojunction light-emitting diodes at forward and reverse bias
Journal
IEEE Photonics Technology Letters
Journal Volume
20
Journal Issue
21
Pages
1772-1774
Date Issued
2008
Author(s)
Abstract
Ultraviolet (UV) light-emitting diodes composed of n-ZnO : Al-SiO 2-ZnO nanocomposite/p-GaN :Mg heterojunction were fabricated on the (0002) Al2O3 substrate. A SiO2 layer embedded with ZnO nanodots was prepared on the p-type GaN using spin-on coating of SiO2 nanoparticles together with atomic layer deposition (ALD). An n-type Al-doped ZnO layer was deposited also by ALD. The SiO2-ZnO nanocomposite layer accomplishes a role of the current blocking layer and also causes, by its low refractive index, the increase in the light extraction efficiency from n-ZnO. Significant UV electroluminescence from n-ZnO was achieved at a low forward-bias current of 1.8 mA. Strong UV emission arising from impact ionization in GaN, ZnO, and GaN :Mg states was also observed at reverse breakdown bias. © 2008 IEEE.
Type
journal article