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

Abstract

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.

Chemical nature of the anion antisite in dilute phosphide GaAs1−xPx alloy grown at low temperature

“…In this case, group-V elements are also incorporated on cation lattice sites, giving rise to group-V antisites [3][4][5]. Such a low-temperature growth regime has been much less investigated for ternary compounds [6][7][8][9] and it is an open question whether the excess of anion atoms incorporated on the cation sublattice follows the same fraction of group-V elements incorporated on the anion sublattice. Because antisites are known to introduce defect states in the band gap of materials that trap free charge carriers and pin the Fermi level, controlling their chemical nature and thus the energy of the defect states would provide an additional degree of freedom in the generation of electromagnetic waves with ternary III-V compounds in the terahertz frequency range [10][11][12][13].…”

Plasmon-enhanced LT-GaAs/AlAs heterostructure photoconductive antennas for sub-bandgap terahertz generation

“…Whereas InGaAs is known as a common semiconductor material for telecommunication window absorption, it is more expensive, has lower conductivity and a longer carrier lifetime than low-temperature-grown GaAs (LT-GaAs) [36,38,43,44]. In fact, plasmon-enhanced LT-GaAs (PE-LT-GaAs) operating at 1.57 µm can outperform InGaAs-based devices, as was previously demonstrated by our group [45,46].…”

“…These applications require a compact, low cost and portable terahertz (THz) system to operate outside the laboratory environment, which is the goal of many recent works [25][26][27]. Among them, there is a growing interest in using photoconductive antennas (PCAs) as the most common approach for THz wave generation [28][29][30] and recent developments have been focused on PCAs operating in the telecom wavelength window [31][32][33][34][35][36][37][38][39][40][41][42] where low-cost high-power fiber-based components are available.…”

High-Power Lensless THz Imaging of Hidden Objects

“…However, in the imaging experiment we aimed for the simplest possible setup (oscillator driven, without external pulse compression modules). For full THz field reconstruction, we use a fiber-coupled photoconductive antenna (PCA) from Fraunhofer Heinrich-Hertz-Institute, Berlin, Germany based on an InAlAs/InGaAs heterostructure [33]. A 1-m single-mode, polarizationmaintaining fiber is attached to the module to direct the probe laser beam to the antenna.…”