Growth and characterization of ErAs:GaBixAs1−x

Abstract

We explore the growth and characterization of ErAs:GaBiAs as a candidate material for terahertz generation and detection via photoconductive switches. Spectrophotometry shows that the incorporation of small amounts of bismuth causes a reduction in the band gap, making these materials compatible with fiber-coupled lasers. ErAs pins the Fermi level within the band gap, causing high dark resistance while maintaining high mobility, shown by Hall effect measurements. Finally, transient absorption (optical pump, optical probe) measurements show that the ErAs provides a carrier recombination pathway, causing short carrier lifetimes. These material properties make ErAs:GaBiAs an interesting choice for fiber-coupled photoconductive switches.

Principles of spintronic THz emitters

“…There has been substantial progress in the development of new III-V materials such as GaBi x As 1−x , which reduces the bandgap, and ErAs:GaAs or TbAs:GaAs, in which the rare-earth (e.g. ErAs) forms nanoinclusions that mediate extremely fast carrier relaxation [23][24][25][26][27][28][29][30][31][32][33][34] . These materials offer significant opportunities for increased control over band structure and carrier dynamics within the PCA substrate.…”

Growth rate and surfactant-assisted enhancements of rare-earth arsenide InGaAs nanocomposites for terahertz generation

“…Carrier lifetimes also showed a modest improvement of ∼11%, achieving a lifetime as low as 1.6 ps for a 2.8 ML LuAs deposition superlattice, despite the rather large 40 nm superlattice period. Future studies should (1) apply these enhancements to shorter period superlattices to yield <1 ps lifetimes and (2) introduce antimony and/or dilute amounts of bismuth 24 into the InGaAs matrix to further improve the dark resistivity and lifetime. …”

“…16 Previous and current photoconductive materials work has focused mainly on low-temperaturegrown (LTG) GaAs, 17 superlattices of epitaxially embedded ErAs [18][19][20] and LuAs [21][22][23] nanoparticles in GaAs, and co-deposited nanoparticles of ErAs in a dilute-bismide matrix of GaAsBi. 24 The recent ErAs:GaAsBi approach reported by Bomberger et al is a noteworthy advance as these materials exhibited excellent dark resistivity and can be pumped with longer-wavelength sources, though more work is needed to achieve high carrier mobilities at the low growth temperatures that are required for dilute-bismide growth. Development of fast photoconductive materials with smaller bandgaps, such as In 0.53 Ga 0.…”

Crystalline quality of GaAs1−x Bi x grown below 250 °C using molecular beam epitaxy

“…i-containing GaAs-based III-V compound semiconductors have recently attracted significant attention as promising materials for semiconductor laser diodes with near-infrared wavelengths, [1][2][3][4] solar cells, 5,6) spintronic devices, 7,8) and so on. Photoconductive antennas (PCAs) for terahertz (THz)-wave emission and detection have been proposed [9][10][11][12][13][14][15] as another application of the Bi-containing GaAs-based semiconductors. Conventional PCAs are fabricated using low-temperature-grown (LTG) GaAs and modelocked Ti:sapphire lasers with 0.8 μm wavelengths as light sources.…”

“…[22][23][24] Within GaAs-based compound semiconductors with bandgaps in the 1.5 μm waveband, some contrivances have been reported to obtain the above-described properties. [12][13][14][15][16][18][19][20][21]25) The kinds of defects within the crystals and their energy levels at the bandgaps are still unclear. In addition to doping, 26) controlling the energy levels of the conduction and valence band edges and the defect levels is a rational approach to locate the Fermi levels at mid-gap in materials for PCAs activated by 1.5 μm wavelength lasers.…”