In recent years, there has been interest in lanthanide monopnictide (Ln-V) nanoparticles (especially ErAs) embedded within III-V semiconductors for photoconductive switches and photomixers for terahertz generation and detection. Photoconductive switches based on ErAs:GaAs have proven quite effective, especially when compared to conventional materials such as low temperature-grown GaAs (LT-GaAs) or radiation-damaged silicon on sapphire. At the same time, the ability to pump a photoconductive switch with 1064nm or 1550nm fiber-coupled lasers rather than titanium-sapphire lasers represents a critical step to wider adoption of terahertz spectroscopy and related technologies.
Accordingly, we report on the growth and characterization of ErAs nanoparticles epitaxially embedded within GaBiXAs1-X. The incorporation of bismuth into III-V semiconductors has been shown to reduce the bandgap, and here, we demonstrate that such ErAs:GaBiAs nanocomposite materials have the requisite electrical and optical properties (i.e. appropriate bandgap, high dark resistance, high mobility, and short carrier lifetime) to be promising materials for photoconductive switches and photomixers operating at 1064nm and longer optical wavelengths. We will also discuss approaches to further extend this wavelength. Additionally, we will discuss our recent work on TbAs-containing materials in which the trap states associated with the nanoparticles can be saturated, providing carrier lifetimes that depend strongly on optical fluence. We believe these materials might provide a path to new terahertz device technologies.