Elastic Properties of GaN and AlN Films Formed on SiC/Si Hybrid Substrate, a Porous Basis
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tic Properties of GaN and AlN Films Formed on SiC/Si Hybrid Substrate, a Porous Basis A. S. Grashchenkoa,*, S. A. Kukushkinb,c,d, and A. V. Osipovb a ITMO
University, St. Petersburg, 197101 Russia Institute for Problems in Mechanical Engineering of the RAS, St. Petersburg, 199078 Russia c Peter the Great St. Petersburg Polytechnic University, St. Petersburg, 195251 Russia d Herzen State Pedagogical University of Russia, St. Petersburg,191186 Russia * e-mail: [email protected]
b
Received August 3, 2019; revised August 11, 2019; accepted September 19, 2019
Abstract—The nanoindentation method was used to study the elastic properties of gallium nitride and aluminum nitride films grown on nanoscale silicon carbide on silicon (SiC/Si), a new type of substrate. The values of the Young’s modulus of epitaxial films of such wide-gap semiconductors as GaN and AlN, grown on substrates SiC/Si. were determined for the first time. It was experimentally established using the nanoindentation method that the Young’s modulus of the GaN epitaxial layer on SiC/Si is 265 GPa, and that of the AlN film is 223 GPa. Using atomic force microscopy and spectral ellipsometry, the structural characteristics of gallium nitride and aluminum nitride films have been studied. The thicknesses of the films and the roughness of their surface are determined. Keywords: nanoindentation, films, Young’s modulus, semiconductors, gallium nitride, aluminum nitride DOI: 10.3103/S0025654420020107
INTRODUCTION Materials based on wide-band semiconductors of the А3В5 group (GaN, AlN) are widely used in the manufacture of optoelectronic devices and devices. The key link in the production of optoelectronic devices is the technology for producing defect-free and low-dislocation layers of gallium nitride (GaN) and aluminum nitride (AlN). Due to the absence of native substrates, the GaN and AlN layers are mainly grown on the substrates of sapphire (Al2O3) and silicon carbide (SiC). A serious obstacle to the widespread use of these substrates is the high cost of SiC substrates and the low conductivity of sapphire substrates. Currently, silicon (Si) holds a special place in the electronics manufacturing segment, where it occupies almost 80% of the electronics and optoelectronics market segment. Since Si is a widespread material that has good conductivity and low cost, the attention of many research groups is focused on silicon as the substrate material for the growth of III-nitride semiconductors. However, a significant difference in the lattice parameters of Si and GaN (16%) and in the coefficients of their thermal expansion (1.5 times) is a serious obstacle in solving this problem. In this regard, many researchers are currently intensively searching for new buffer layers that could be grown on silicon and which would provide relaxation of elastic stresses in the GaN and AlN layers grown on Si and, thus, block the formation of misfit dislocations in the bulk of these films. In a series of works [1–3], a new, cheap method for the synthesis of epitaxial layers of silic
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