Silicon nanowire heterostructures for advanced energy and environmental applications: a review

Abstract

Semiconductor nanowires (NWs), in particular Si NWs, have attracted much attention in the last decade for their unique electronic properties and potential applications in several emerging areas. With the introduction of heterostructures (HSs) on NWs, new functionalities are obtained and the device performance is improved significantly in many cases. Due to the easy fabrication techniques, excellent optoelectronic properties and compatibility of forming HSs with different inorganic/organic materials, Si NW HSs have been utilized in various configurations and device architectures. Herein, we review the recent developments in Si NW HS-based devices including the fabrication techniques, properties (e.g., light emitting, antireflective, photocatalytic, electrical, photovoltaic, sensing etc) and related emerging applications in energy generation, conversion, storage, and environmental cleaning and monitoring. In particular, recent advances in Si NW HS-based solar photovoltaics, light-emitting devices, thermoelectrics, Li-ion batteries, supercapacitors, hydrogen generation, artificial photosynthesis, photocatalytic degradation of organic dyes in water treatment, chemical and gas sensors, biomolecular sensors for microbial monitoring etc have been addressed in detail. The problems and challenges in utilizing Si NW HSs in device applications and the key parameters to improve the device performance are pointed out. The recent trends in the commercial applications of Si NW HS-based devices and future outlook of the field are presented at the end.

Prologue: Nanorods – Recent Advances and Future Perspective

“…A noble metal nanoparticle is used as a catalyst to start the growth of the NRs. The shape and size, density, and quality of the NRs are controlled by several parameters: (i) the size and shape of the metal nanoparticles, (ii) intermediate distance between the nanoparticles, (iii) etching parameters (concentration and temperature of the etching solution, and etching time duration), and (iv) crystal quality and orientation of the starting wafer [13]. Both the above-mentioned processes are generally anisotropic, and the use of a protective layer/masking is very important to get uniform NRs.…”

High-Speed and Direction-Controlled Formation of Silicon Nanowire Arrays Assisted by Electric Field

“…Low-dimensional silicon (Si) nanostructures displayed remarkable electronic, mechanical, and optoelectronic properties that could act as building elements of functional devices and applications [1][2][3], such as field-effect transistors, biosensors, and photovoltaic cells [4][5][6][7][8][9]. To form the regular arrays of Si nanostructures, metalassisted chemical etching has been considered the prevailing strategy that even enabled to form Si nanowire (SiNW) arrays on planar substrates [10,11], powders [12,13], and pyramidal structures [14].…”

A silicon-based quantum dot random laser

“…7 The Si NWs fabricated by the MACE method have attracted broad attention due to their fantastic properties and potential applications. [8][9][10][11][12] During the MACE process, the length of the Si NWs increases with an increase in the etching time. Moreover, a mesoporous structure is formed on the NW side walls due to crystal defects and impurities, such as dopants, in the p-type Si.…”