Terahertz detectors from Be-doped low-temperature grown InGaAs/InAlAs: Interplay of annealing and terahertz performance

The influence of post-growth annealing on the electrical properties, the transient carrier dynamics and the performance as THz photoconductive receiver of Beryllium (Be) doped InGaAs/InAlAs multilayer heterostructures grown at 130 °C in a molecular beam epitaxy (MBE) system was investigated. We studied samples with nominally Be doping concentrations of 8 ×10 17 cm-3 – 1.2 ×1019 cm3 annealed for 15 min. – 120 min. at temperatures between 500 °C – 600 °C. In contrast to previous publications, the results show consistently that annealing increases the electron lifetime of the material. In analogy to the annealing properties of low-temperature grown (LTG) GaAs we explain our findings by the precipitation of arsenic antisite defects. The knowledge of the influence of annealing on the material properties allowed for the fabrication of broadband THz photoconductive receivers with an electron lifetime below 300 fs and varying electrical properties. We found that the noise of the detected THz pulse trace in time-domain spectroscopy (TDS) was directly determined by the resistance of the photoconductive receiver and the peak-to-peak amplitude of the THz pulse correlated with the electron mobility.