Solar Energy Materials & Solar Cells 204 (2020) 110217 Available online 18 October 2019 0927-0248/© 2019 Elsevier B.V. All rights reserved. Fabrication and studies on Si/InP core-shell nanowire based solar cell using etched Si nanowire arrays Biswajit Pal a , Kalyan Jyoti Sarkar b , Pallab Banerji a, * a Materials Science Centre, Indian Institute of Technology, Kharagpur, 721302, India b Advanced Technology Development Centre, Indian Institute of Technology, Kharagpur, 721302, India A R T I C L E INFO Keywords: Core-shell structure Solar cell Silicon nanowire MOCVD ABSTRACT We report Si/InP core-shell nanowire radial heterojunction array based solar cell. Silicon nanowire (SiNW) ar- rays were fabricated by room temperature metal assisted chemical etching method on a p-type Si (100) wafer using silver nanoparticles whereas n-InP layer, as a shell, was deposited onto the SiNW arrays by atmospheric pressure metal organic chemical vapor deposition to obtain core-shell radial heterojunctions. A 100 nm trans- parent conductive oxide layer was deposited onto top of n-InP layer by sputtering. Transmission electron mi- croscope images confrm the formation of Si/InP core-shell radial nanowire heterostructure. From the studies of refectance spectroscopy, higher absorption of visible photons has been found. Current-voltage measurements on the radial core-shell nanowire heterojunction based solar cell have been taken under dark and an AM 1.5 solar radiation at room temperature. The device is found to provide a conversion effciency of 4.39% with an open circuit voltage of 0.56 V and a short circuit current density 14.26 mA/cm 2 under AM 1.5 solar radiation. The core-shell radial heterojunction solar cell on nanowire arrays shows great improvement of the performance in comparison with conventional nanowire based solar cells. Our study provides new insights into the Si/InP core- shell nanowire based heterojunction which can have potential applications in fabricating nanoscale optoelec- tronic devices on Si platform. 1. Introduction InP based solar cells have been considered as future candidates for space applications due to their excellent radiation resistance and high conversion effciency [1]. In space applications, however, it is important to keep the weight of the solar cells as less as possible without compromising the mechanical strength of the material. Though InP has a lower electron mobility of 4100 cm 2 /Vs compared to GaAs (8000 cm 2 /Vs), the electrons exhibit a higher saturation velocity of 2.2 � 10 7 cm/s in the former compared to the later (1.2 � 10 7 cm/s) [2]. Thus InP is a good candidate for faster devices under high electric feld. In addition, it has other advantages such as lower surface recombination velocity, lower compensation in bulk, and epi layers, etc [3]. It is also used as high frequency power devices due to higher thermal conductivity. However, InP has high material density (4.81 g/cm 3 ) and itself is extremely brittle prohibiting reasonably thinning the InP for its use in solar cell as a substrate. Moreover the cost of InP substrate is exorbi- tantly high. To overcome such problems, heteroepitaxial growth of InP on foreign substrates such as GaAs and Si, has been attempted by some groups [4–6]. However, heteroepitaxial structures have a high amount of misft dislocation which reduces the minority carrier life time. This worsens the solar cell electrical characteristics. To minimize the effect of dislocation, heteroepitaxially growth of InP on suitable one dimensional nanostructures can be a good idea, which will relief of effective strain energy at the heterointerface [7]. Moreover, it has been postulated that such kind of heterostructure can form a type-II heterojunction such as InP on silicon [8], which will accelerate the separation of photo-excited electron-hole pairs and improve the effciency of solar cells. In recent years, there has been a great demand for the development of the next generation solar cells with higher effciency, longer life, and cheaper price. Solar cells based on one dimensional nanomaterials and nanostructures such as nanowires, nanorods, and nanotubes are prom- ising candidates in terms of their performance by improving light trapping and photo carrier collection [9,10]. In the past two decades, to improve effciency of the photovoltaic response, device structures including axial architecture [11,12], radial architecture (core-shell) [13–15], and nanostructures embedded in thin flms have been studied * Corresponding author. E-mail address: pallab@matsc.iitkgp.ac.in (P. Banerji). Contents lists available at ScienceDirect Solar Energy Materials and Solar Cells journal homepage: http://www.elsevier.com/locate/solmat https://doi.org/10.1016/j.solmat.2019.110217 Received 24 May 2019; Received in revised form 8 September 2019; Accepted 8 October 2019