Investigation of crystallinity and planar defects in the Si nanowires grown by vapor–liquid–solid mode using indium catalyst for solar cell applications

Abstract

Stacking-fault-free and planar defect (twinning plane)-free In-catalyzed Si nanowires (NWs) are essential for carrier transport and nanoscale device applications. In this article, In-catalyzed, vertically aligned, and cone-shaped Si NWs on Si(111) were grown successfully, in the vapor–liquid–solid (VLS) mode. In particular, the influences of substrate temperature (T S) and cooling rate (ΔT S/Δt) on the formation of planar defects, twinning planes along the [112] direction, and stacking faults in Si NWs were investigated. When T S was decreased from 600 °C to room temperature at a rate of 100 °C/240 s after Si NW growth, twinning plane defects perpendicular to the substrate and along different segments of (111)-oriented Si NWs were observed. Finally, one simple model was proposed to explain the stacking fault formation as well as Si NW length limitation due to the In-nanoparticle (In-NP) migration, and root causes of the twinning plane defects in the Si-NWs.

Indium (In)-Catalyzed Silicon Nanowires (Si NWs) Grown by the Vapor–Liquid–Solid (VLS) Mode for Nanoscale Device Applications

“…Different planar defects along the axial segments and twining of planar defects has been shown at point S-I and S-II, respectively. Figure 4 reproduced with the permission from ref [43]. Copyright 2016 the Japan Society of Applied Physics (JSAP).…”

ZnO@TiO2 Core/Shell Nanowire Arrays with Different Thickness of TiO2 Shell for Dye-Sensitized Solar Cells

“…One-dimensional (1-D) nanostructures can effectively eliminate the shortage mentioned above, because the grain boundaries effect could be restricted [8,9]. Moreover, 1-D nanostructures, such as aligned vertically nanowire or nanotube arrays, could provide short electron transmission pathways which ensure the rapid collection of photo-generated carriers throughout the device [10][11][12]. ZnO owns higher electron mobility than that of TiO 2 , by 2-3 orders of magnitude.…”

“…For example, Xu CK et al [21] assembled four layers of ZnO nanowire arrays with thickness of up to 40 µm, for using as an anode of DSSCs, with power conversion efficiencies of up to 7%. However, the growth of long nanowires is commonly time consuming [12]. So, this is an effective method to deposit a shell on these 1-D nanostructures, to increase the surface roughness.…”

Theoretical investigation about the optical characterization of cone‐shaped pin‐Si nanowire for top cell application

“…Among bottom-up Si NW growth methods, vapor liquid solid (VLS) mode-based Si NW growth is getting a great deal of attention because of its low-cost processing technique [24]. There have been many reports of bottom-up Si NW growth methods using various materials as a catalyst, such as Au, Al, Ga, In, Pb, Sn, and Zn, via VLS mechanisms [7,9,10,[25][26][27][28][29][30][31][32][33]. Au-catalyzed Si NWs grown using VLS might not be useful for solar cell applications because they create a deep acceptor level at 0.54 eV in the Si band gap, whereas the In catalyst creates a shallow accepter level at 0.16 eV in the Si band gap and can suppress the degradation of minority carrier lifetime [32].…”

“…Recently, we successfully controlled the verticality of Si NWs with good crystalline quality. In-catalyzed based Si NWs grown using the VLS mode produced cone-shaped Si NWs because of catalyst trapping by the NWs [32,33]. Ball et al [34], investigated the optical characteristics of conical Si NWs and focused on the influence of the Sn catalyst thickness layer and NWs densities on the optical characteristics.…”