Regular Article

Ultrafast carrier dynamics of aluminum-doped silicon film irradiated by femtosecond laser pulse

¹ Department of Physics, College of Science, Northeast Forestry University, 150040 Harbin, P.R. China
² Department of Physics, Tsinghua University, 100084 Beijing, P.R. China
³ School of Electronic Engineering, Heilongjiang University, 150080 Harbin, P.R. China

^a e-mail: hanyaping@nefu.edu.cn

Received: 3 September 2016
Revised: 9 December 2016
Accepted: 23 January 2017
Published online: 12 April 2017

Abstract

An aluminum-doped p-type polycrystalline silicon film was fabricated on a glass substrate using magnetron sputtering. The ultrafast carrier dynamics of the silicon film were studied via its femtosecond transient reflectivity characteristics. The analysis of the transient reflectivity signal shows that the fast component of the relaxation time Ƭf is shorter than that found in previous studies with undoped silicon. The dynamics of the free carrier response and state filling dominate Ƭf in this sample, and owing to the existence of defects and boundaries, the state filling effect significantly increases Ƭf. On a longer time scale, the Auger recombination and carrier diffusion dominate the relaxation process. The slow component of the relaxation time Ƭfs is also shorter than any previously reported values for undoped silicon films.