Carbon Irradiated SI-GaAs for Photoconductive THz Detection
  We report here a photoconductive material for THz generation and detection with sub-picosecond carrier lifetime made by C12 (Carbon) irradiation on commercially available semi-insulating (SI) GaAs. We are able to reduce the carrier lifetime of SI-GaAs down to sub-picosecond by irradiating it with various irradiation dosages of Carbon (C12) ions. With an increase of the irradiation dose from ~1012 /cm2 to ~1015 /cm2 the carrier lifetime of SI-GaAs monotonously decreases to 0.55 picosecond, resulting in strongly improved THz pulse detection compared with normal SI-GaAs. 
Abhishek Singh, Sanjoy Pal, Harshad Surdi, S. S. Prabhu, Mathimalar   S., Vandana Nanal, R. G. Pillay and G.H. Dohler
cond-mat.mtrl-sci physics.optics