[15a-PB5-1~4] 13.6 Semiconductor English Session

▲ [15a-PB5-3] Externally applied magnetic field-effects on the terahertz emission
from p-type and n-type InAs wafers

Alexander De Los Reyes¹, 〇(B)Elmer Estacio¹ (1.National Institute of Physics, University of the Philippines Diliman)

キーワード：Terahertz

We propose a new insight on the origin of the magnetic field enhancement of the terahertz emission in femtosecond laser excited Indium Arsenide (InAs) surfaces. Magnetic field effects on the TeraHertz Time-Domain Spectroscopy (THz-TDS) line-shape were studied for both upward and downward magnetic field orientations using a 650 mT magnet applied parallel to the surface and perpendicular to the reflection plane. A 180 phase-shift was observed in both the p- and n-InAs samples upon reversal of the magnetic field orientation. Furthermore, the magnetic field-enhancement in p-InAs is higher when the magnetic field orientation is upward while the magnetic field-enhancement in n-InAs is higher when the magnetic field orientation is downward. We present these magnetic field enhancement results as a consequence of an increased contribution of the surface field-induced drift surge current which was generally perceived to be non-dominant in InAs [1, 2]. The general effect of the magnetic field aside from the net rotation of the terahertz dipole is to induce cyclotron motion of the photo-electrons, forcing these carriers to spend more time in the surface depletion region rather than simply undergoing transport towards the bulk when there is no magnetic field. We propose this mechanism as a possible enhancement mechanism that may occur simultaneously as an additional enhancement to the widely-accepted mechanism of dipole-reorientation.