Terahertz Emitters and Detectors Made on High-Resistivity InGaAsP:Fe Photoconductors

A terahertz (THz) time-domain spectrometer built entirely from a pair of emitter and detector made on ion-implanted InGaAsP:Fe substrates is characterized for the first time. THz waveforms are measured as a function of the excitation power and the emitter's bias voltage on different standard stripline photoconductive antennas. The photoconductive property of the implanted materials is further enhanced by a thermal annealing treatment. The photocarrier mobility in the photoconductive layer is extracted from the THz saturation and estimated at 5 cm
²
V
^-1
s
^-1
. The presence of an InP cap layer during the thermal annealing treatment is found to affect the resistivity profile of the implanted materials, which also impacts on the performance of the THz emitter. Under optimized conditions and triggered by 280 fs laser pulses at 1550 nm, the spectrometer offers a 1.4-THz 20-dB bandwidth and a spectrum with a 65-dB peak dynamic range.