Improved Performance of GaAs-Based Terahertz Emitters via Surface Passivation and Silicon Nitride Encapsulation

Author

Headley, Carl ; Fu, Lan ; Parkinson, Patrick ; Xu, Xinlong ; Lloyd-Hughes, James ; Jagadish, Chennupati ; Johnston, Michael B.

Author_Institution

Dept. of Phys., Univ. of Oxford, Oxford, UK

Volume

17

Issue

1

fYear

2011

Firstpage

17

Lastpage

21

Abstract

We have improved the stability and performance of terahertz (THz) photoconductive (Auston) switches using a combination of (NH₄)₂S surface passivation (SP) and silicon nitride (Si₃N₄) encapsulation. The influences of SP and encapsulation on the ultrafast electron dynamics in GaAs were examined using THz emission spectroscopy and optical pump-THz probe spectroscopy. The power of THz radiation from the surface of photoexcited GaAs increased by a factor of 5 after passivation and encapsulation, while the process lengthened the trapping time for photoexcited charge carriers. By fabricating and assessing the performance of photoconductive switches, we found that passivation and encapsulation increased the average THz power generated fourfold.

Keywords

III-V semiconductors; encapsulation; gallium arsenide; passivation; photoconducting switches; silicon compounds; submillimetre wave generation; submillimetre wave spectroscopy; GaAs; SiN; optical pump-terahertz probe spectroscopy; photoconductive switches; silicon nitride encapsulation; surface passivation; terahertz emission spectroscopy; terahertz emitters; trapping time; ultrafast electron dynamics; Photoconductive switch (PCS); surface passivation (SP); terahertz (THz); time-domain spectroscopy;

fLanguage

English

Journal_Title

Selected Topics in Quantum Electronics, IEEE Journal of

Publisher

ieee

ISSN

1077-260X

Type

jour

DOI

10.1109/JSTQE.2010.2047006

Filename

5460898