Growth and properties of rare-earth arsenide InGaAs nanocomposites for terahertz generation

Abstract

We explore the effects of surfactant-mediated epitaxy on the structural, electrical, and optical properties of fast metal-semiconductor superlattice photoconductors. Specifically, application of a bismuth flux during growth was found to significantly improve the properties of superlattices of LuAs nanoparticles embedded in In 0.53 Ga 0.47 As. These improvements are attributed to the enhanced structural quality of the overgrown InGaAs over the LuAs nanoparticles. The use of bismuth enabled a 30% increase in the number of monolayers of LuAs that could be deposited before the InGaAs overgrowth degraded. Dark resistivity increased by up to $15Â while carrier mobility remained over 2300 cm 2 /V-s and carrier lifetimes were reduced by >2Â at comparable levels of LuAs deposition. These findings demonstrate that surfactant-mediated epitaxy is a promising approach to enhance the properties of ultrafast photoconductors for terahert generation.

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

“…26,37 The Hall measurements showed a gradual increase in dark resistivity with increasing depositions of LuAs, shown in Fig. 2(a), consistent with previous studies of RE-As:InGaAs superlattices where the RE-As nanoparticles act as recombination centers at higher depositions, reducing the mobility and conductivity.…”

“…Prior studies of LuAs-based nanocomposites 21,37 indicate nucleation of LuAs nanoparticles before the formation of films when grown on zincblende iii-v materials, similar to other RE-V monopnictides. 53,54 The growth rate of the RE-As 42 and the amount deposited 21,[55][56][57] affect the density 096106-3 Salas et al…”

“…Our previous studies of superlattices containing different RE-As species suggested that the quality of the matrix overgrowth could have a considerable impact on nanocomposite properties. 37 Aside from previous studies into various growth temperatures in GaAsbased nanocomposites, 41 there has been little research exploring nanoparticle morphology as a means to improve the structural quality of the matrix in superlattices and its effects on the photoconductive properties. Moreover, the role of the RE-V growth rate has been only scarcely studied and yielded mixed results.…”

“…25,26 Despite considerable efforts with small bandgap materials using InP-based 34 devices based on such materials have yet to yield output powers beyond the microwatt range at THz frequencies. Nanocomposites based on rare-earth arsenide (RE-As) nanoparticle superlattice [35][36][37] and codeposited [38][39][40] structures in an InGaAs matrix have also been investigated but were found to exhibit prohibitively low dark resistivities. Our previous studies of superlattices containing different RE-As species suggested that the quality of the matrix overgrowth could have a considerable impact on nanocomposite properties.…”

“…The superlattice structure consisted of a 150-nm InGaAs buffer layer followed by 30 periods of LuAs deposition with 40 nm of InGaAs overgrowth, similar to previous structures investigated to facilitate direct comparison. 37,44 All samples used constant LuAs depositions per period except for those used for transmission electron microscopy (TEM) studies, which varied in the amount of LuAs deposited per period. Specifically, TEM structures began with depositions of 0.2 ML in the first period and increased by 0.2 ML per period up to 3.0 ML.…”