ISSN 1062-8738, Bulletin of the Russian Academy of Sciences: Physics, 2010, Vol. 74, No. 1, pp. 65–68. © Allerton Press, Inc., 2010. Original Russian Text © E.V. Astrova, V.A. Tolmachev, G.V. Fedulova, V.A. Melnikov, T.S. Perova, 2010, published in Izvestiya Rossiiskoi Akademii Nauk. Seriya Fizicheskaya, 2010, Vol. 74, No. 1, pp. 74–77. 65 INTRODUCTION Photonic crystals (PCs) based on silicon can be obtained using different microstructuring methods. They are of great interest in the development of silicon microphotonic and optoelectronic elements in which the light propagates in-plane, as they are well inte- grated into the existing technology of integrated cir- cuits and allow a light beam to be transformed inside a chip. Among the different methods of obtaining peri- odic structures with a high aspect ratio, the most attractive is liquid-phase etching. As shown in our pre- vious work [1], the chemical anisotropic etching of Si(110) is quite convenient in fabricating one-dimen- sional PCs. These were used as the basis for manufac- turing composite PCs for the near infrared region with tunable photonic band gaps (PBGs) [2, 3]. An alterna- tive technology for forming periodic wall array struc- tures is the process of photoelectrochemical etching of Si(100) [4, 5], which was first used to obtain discrete macropores from point nucleation sites (seed holes) [6–8]. The method for obtaining deep wall arrays is based on the formation of a semiregular macropore lattice in samples with grooves on the surface (i.e., lin- ear seeds; see inset in Fig. 1) when the pores align along the seed grooves and can coalesce under certain conditions into a single wall array [9, 10] (Fig. 1). An advantage of this technology is being able to use Si(100) and not having to align precisely the groove pattern in-plane, as is required in the case of aniso- tropic etching of Si(110). Barillaro et al. [11, 12] studied the possibility of using such structures with a period of a = 3 μm as one-dimensional PCs for the near infrared region (λ = 1.5 μm). One-Dimensional Photonic Crystal Fabricated by the Photochemical Etching of Silicon E. V. Astrova a , V. A. Tolmachev a , G. V. Fedulova a , V. A. Melnikov b , and T. S. Perova b a Ioffe Physical and Technical Institute, Russian Academy of Sciences, St. Petersburg, 194021 Russia b Department of Electronic and Electrical Engineering, Trinity College, Dublin 2, Ireland e-mail: east@mail.ioffe.ru Abstract—The formation of periodic wall arrays on an n-type (100) Si substrate with V-shaped seed grooves on the surface was investigated. The influence of silicon sidewall roughness on the optical properties of one- dimensional (1D) of photonic crystals obtained on the basis of the arrays was studied. The reflection spectra of the 1D photonic crystals exhibit a high modulation level of up to 95% and photonic band gaps of a high order that are in good agreement with calculations over a wide spectral range (1.5–15 μm). DOI: 10.3103/S106287381001017X 1 μm (a) 10 μm 10 μm (b) Fig. 1. SEM image of the cross section of a structure with seed groove period a = 4 μm obtained on silicon with ρ = 5 Ω ⋅ cm, (a) across wall arrays and (b) along wall arrays. The square designates the illuminated region and its depth, as measured from the upper sample surface. Inset: SEM image of seed grooves on the sample surface.