Title: | Terahertz emission from Mg-doped a-plane InN |
Authors: | Ahn, H. Yeh, Y. -J. Gwo, S. 光電工程學系 Department of Photonics |
Keywords: | nonpolar indium nitride;terahertz emission;in-plane electric field |
Issue Date: | 2011 |
Abstract: | We report terahertz (THz) emission from magnesium doped a-plane indium nitride (a-InN:Mg) films with different background carrier density, relative to the Mg-doped InN films grown along the c-axis (c-InN: Mg). Due to its high electron affinity, as-grown InN film is typically n-type and it has extremely high background carrier density, which causes much weaker THz emission than that from other semiconductors, such as InAs. The background carrier density of Mg-doped InN can be widely changed by adjusting the Mg doping level. For c-InN: Mg, THz emission is dramatically enhanced (x500 than that of undoped c-InN) as the background carrier density decreases to a critical value of similar to 1x10(18) cm(-3), which is due to the reduced screening of the photo-Dember field at the lower carrier density. For a-InN, however, intense THz emission (x400 than that of undoped c-InN) is observed for both undoped and Mg-doped a-InN and the enhancement is weakly dependent on the background carrier density. The primary THz radiation mechanism of the a-plane InN film is found to be due to the acceleration of photoexcited carriers under the polarization-induced in-plane electric field perpendicular to the a-axis, which effectively enhances the geometrical coupling of the radiation out of semiconductor. The weak dependence of THz radiation on the background carrier density for a-InN shows that in-plane surface field induced-terahertz emission is not affected by the background carrier density. Small, but apparent azimuthal angle dependence of terahertz emission is also observed for a-InN, indicating the additional contribution of nonlinear optical processes on terahertz emission. |
URI: | http://hdl.handle.net/11536/2241 http://dx.doi.org/10.1117/12.874400 |
ISBN: | 978-0-81948-482-6 |
ISSN: | 0277-786X |
DOI: | 10.1117/12.874400 |
Journal: | QUANTUM SENSING AND NANOPHOTONIC DEVICES VIII |
Volume: | 7945 |
Appears in Collections: | Conferences Paper |
Files in This Item:
If it is a zip file, please download the file and unzip it, then open index.html in a browser to view the full text content.