Terahertz emission from metal-organic chemical vapor deposition grown Fe:InGaAs using 830 nm to 1.55 μm excitation

Abstract

We demonstrate the generation of broadband terahertz (THz) frequency radiation from photoconductive emitters formed from Fe-doped InGaAs (Fe:InGaAs), grown by metal-organic chemical vapor deposition, following pulsed (femtosecond) laser excitation at wavelengths ranging from 830 nm to 1.55 μm. The Fe is incorporated epitaxially during growth, giving precise control over the doping level. Using both single-crystal ZnTe and GaP electro-optic detectors over the same wavelength range, the emission spectra from several Fe:InGaAs wafers with different Fe content were measured, with THz emission from all wafers showing bandwidths in excess of 2.0 THz. The THz output power was found to be strongly dependant on the Fe content, the thickness of the Fe:InGaAs layer, and the excitation wavelength.