New Lines in High Resolution IR Luminescence Spectra of SiC Single Crystals of the 4H and 6H Polytypes
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New Lines in High Resolution IR Luminescence Spectra of SiC Single Crystals of the 4H and 6H Polytypes K. N. Boldyreva, b, *, D. D. Gutsenkoa, b, S. A. Klimina, N. N. Novikovaa, B. N. Mavrina†, M. N. Mayakovac, and V. M. Khnykovd a Institute
b
for Spectroscopy, Russian Academy of Sciences, Troitsk, Moscow, 108840 Russia Moscow Institute of Physics and Technology (National State University), Dolgoprudnyi, Moscow oblast, 141700 Russia c Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow, 119991 Russia d OOO “Grannik,” 127051 Moscow, Russia *e-mail: [email protected] Received March 15, 2020; revised May 15, 2020; accepted May 20, 2020
Abstract—We have studied high-resolution low-temperature IR luminescence and absorption spectra of undoped high-quality SiC single crystals of the 4H and 6H hexagonal modifications. Narrow lines with a width of smaller than 0.2 cm–1 have been revealed, with some of which being observed for the first time. We have found that some of the lines in the 4H and 6H modifications have similar structures; however, the lines in SiC-4H are shifted to the high-energy part of the spectrum by ~180 cm–1. For the most intense quartet in the range of 1.3 μm, we have succeeded in constructing the energy structure of levels for both the 4H modification and the 6H modification based on their luminescence and absorption spectra. Keywords: silicon carbide, SiC, luminescence, high resolution, color centers DOI: 10.1134/S0030400X20090040
INTRODUCTION Silicon carbide (SiC) is an inorganic chemical compound of silicon with carbon. It exists in a number of crystalline forms—polytypes [1], which are characterized by different ways of packing atoms in the unit cell. The structure of the crystal lattice of silicon carbide is such that there are several possible structural forms for one and the same chemical compound, which coincide with each other in two dimensions but differ in the third dimension. Therefore, various polytypes are atomic layers arranged in a certain sequence. Polytypes of silicon carbide are characterized by the number of atomic layers in the unit cell and by the type of the Bravais lattice—2H, 3C, 4H, 6H, 15R, etc. Due to the polymorphism of silicon carbide, it has a wide variety of color centers, which are characteristic of various polytypes and are similar in properties to the well-studied NV defects in diamond [2], which are formed due to the coupling between of a carbon vacancy and a nitrogen atom. Wide opportunities for the use of color centers in diamond (in spectroscopy of single quantum objects, quantum computations, quantum magnetometry, etc.) [3–5] stimulated studies on the search for color centers in other substances, in particular, in silicon carbide [6]. Vacancy centers in silicon carbide were † Deceased.
discovered for the first time by the EPR method [7]. Experiments of [8, 9] on optically detected magnetic resonance (ODMR) showed that the spin of the ground state of a vacancy center (V-center, which is formed by bound silico
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