MRS Proceedings


Terahertz Emission from Vertically-aligned Silicon Nanowires

2010 MRS Spring Meeting.

Yong Jae Choa1, Gyeong Bok Junga2, Yoon Myunga3, Han Sung Kima4, Young Suk Seoa5 and Jeunghee Parka6

a1 [email protected], korea university, 5-ka, Anam-dong, Sunbuk-ku, Seoul 136-701, Korea, Seoul, 136-701, Korea, Republic of

a2 [email protected], Korea University, Seoul, Korea, Republic of

a3 [email protected], Korea University, Seoul, Korea University, Korea, Republic of

a4 [email protected], United States

a5 [email protected], Korea University, Seoul, Korea, Republic of

a6 [email protected], Korea University, Seoul, Korea, Republic of


Large-area vertically aligned silicon nanowire (Si NW) arrays were synthesized with a controlled length (0.3 ˜ 9 μm) by the chemical etching of n-type silicon substrates. Upon their excitation using a fs Ti-sapphire laser pulse (800 nm), their THz emission intensity exhibits strong dependence on their length; the intensity increases sharply up to a length of 3 μm and then decreases slightly, due to the complete absorption of the optical pump power. The Raman scattering spectrum exhibits the same behavior as that of the THz emission. We suggest that the field enhancement by localized surface plasmons induces more efficient THz emission or Raman scattering for the longer Si NWs. The photocurrent measured in a photoelectrochemical cell showed consistently the length dependence with a maximum value at the length of 5 μm.

(Received March 25 2010)

(Accepted October 10 2010)

Key Words:

  • Si;
  • Raman spectroscopy;
  • photovoltaic