Invited Talk by Mun Cheol Paek

Author: Mun Cheol Paek; ETRI, Electronics and Telecommunications Research Institute; Korea
Title of the Talk Terahertz Wave Detection Property of Polycrystalline GaAs Layer Irradiated by Ultra-short Laser Pulse
We have investigated the effects of crystal defects on detection of terahertz waves in a polycrystalline GaAs layer irradiated by ultra-short pulse laser. The poly-GaAs layer was grown by a molecular beam epitaxy(MBE) system at abnormally low temperature of 150C and in-situ anneal at 600C. Lifetime and mobility of photo-generated charge carriers in the poly-GaAs layers were measured and compared with those of the normally grown epi-GaAs layers. Grain boundaries in the poly-GaAs layer and As precipitates in the epi-GaAs layers were both responsible for trapping of the charge carriers. Terahertz wave radiation detected with a photoconductive antenna device fabricated by using the poly-GaAs layer showed a higher signal to noise ratio than those of the epi-GaAs layers. Measurement and calculated results of carrier lifetime and terahertz wave detection properties revealed that the grain boundaries are more efficient than the As precipitates for the trapping of the photo-generated carriers.