Lateral photo-Dember effect from MoS2 investigated by THz emission spectroscopy

Abstract

A photo-Dember effect is one of typical THz emission mechanisms, and it occurs from different diffusion of photoexcited electrons and holes. In general, the THz emission arises due to a diffusion of photo-carriers along the depth direction due to the large photo-carrier density gradient in narrow-gap semiconductors. On the other hand, it can arise from the diffusive motion also along the lateral direction in patterned semiconductors, for example, with a metal pad partially covering the sample. Here, we examine the THz emission from MoS2, and find a clear signature of the lateral photo-Dember effect. We discuss in-plane photo-carrier dynamics based on the THz amplitude and spectral shape.