| 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 |
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Abstract:
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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 150°C and in-situ anneal at 600°C. 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.
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