Direct Heteroepitaxy of Vertical InAs Nanowires on Si Substrates for Broad Band Photovoltaics and Photodetection

Abstract

Catalyst-free, direct heteroepitaxial growth of vertical InAs nanowires on Si(111) substrates was accomplished over a large area by metal-organic chemical vapor deposition. Nanowires showed very uniform diameters and a zinc blende crystal structure. The heterojunctions formed at the interface between the n-type InAs nanowires and the p-type Si substrate were exploited to fabricate vertical array photodiode devices which showed an excellent rectification ratio and low reverse leakage current. Temperature-dependent current transport across the heterojunctions was studied theoretically and experimentally in the dark and under AM 1.5 illumination. When operated in photovoltaic mode, the open-circuit voltage was found to increase linearly with decreasing temperature while the energy conversion efficiency changed nonmonotonically with a maximum of 2.5% at 110 K. Modeling of the nanowire/substrate heterojunctions showed good agreement with the experimental observations, and allowed determining the conduction band offset between the InAs nanowires and Si to be 0.10-0.15 eV. The external quantum efficiency and photoresponsivity profiles of the device showed a broad spectral response from the visible to the infrared region, indicating potential applications as a broad band photovoltaic cell or a visible-infrared dual-band photodetector.

Characteristics of Strain-Induced InxGa1–xAs Nanowires Grown on Si(111) Substrates

“…The binary InAs NW, in contrast, is completely vertical along the (111) direction without any bending, as confirmed by previous study. 15,16 The NW bending phenomenon can be understood from the local inhomogeneity of group III composition producing nonuniform strain across the NWs. However, the composition inhomogeneity in ternary NWs occurs only intermittently for a few monolayers, 15 and no systematic trend in composition variation is observed, which will be discussed with the EDX results below.…”

Characterization and analysis of InAs/p–Si heterojunction nanowire-based solar cell

“…Among the applications of III-V arrays on silicon are tunnel diodes [23], photoelectrochemical water splitting [24,25] and solar cells [26,27]. By combining a GaAs nanowire array on a silicon cell, a dual junction with a theoretical efficiency higher than 30% could, in theory, be achieved [28].…”

Influence of growth parameters on In-droplet-assisted growth of InAs nanowires on silicon

“…Semiconducting nanowires (NWs) have been touted as promising building blocks for applications in photonics and electronic devices (Duan et al 2003;Tian et al 2007;Colinge et al 2010;Tomioka et al 2012;Wang et al 2014) due to their unique properties including superior light absorption, enhanced photo-carrier separation, and epitaxial growth insensitive to lattice mismatch (Wei et al 2009). In particular, InAs NWs have garnered enormous research interest due to its narrow direct band gap (0.35 eV), small electron effective mass, and high electron mobility of *30,000 cm 2 /Vs at 300 K (Wallart et al 2005;Ihn and Song.…”

“…Although, Au is commonly used for NWs nucleation, its use is accompanied with the introduction of unwanted impurities and deep level traps (Allen et al 2008), which are detrimental to applications in optoelectronic devices (Bar-Sadan et al 2012). Consequently, there is a paradigm shift towards Au-free technologies including catalyst-free (Wei et al 2009;Dimakis et al 2011;Hwang et al 2015) and droplet-assisted growth (DAG) of NWs (Somaschini et al 2013;Anyebe et al 2014;Ermez et al 2015). Whereas catalyst-free growth is Indium (In) free and requires no catalyst for NWs nucleation, droplet-assisted growth involves the in situ deposition of group-III element droplets (mostly Ga or In seeds) on the substrate prior to growth initiation to function as catalyst for the preferential nucleation of NWs.…”