Temperature dependence of the Raman-active modes in the semipolar (112¯2) plane GaN Film

Abstract

Temperature dependences of the polarized Raman scattering spectra in the backscattering configuration of the semipolar (112¯2) plane GaN thin film are analyzed in the range from 83 K to 563 K. The semipolar GaN film is cut at a tilted angle from polar GaN wafer grown by hydride vapor phase epitaxy. The spectral features of the frequency shift and linewidths of the Raman-active phonon modes Quasi-TO, E1 (TO), E2 (high), and Quasi-LO are prominently revealed, and the temperature coefficients corresponding to the lattice thermal expansion and phonon anharmonic effect, as well as defects and impurities in crystals, are well deduced by the theoretical equations. With the increasing temperature, the Raman scattering peaks would substantially shift to lower frequencies and the linewidths gradually broaden. Our studies will lead to a better understanding of the fundamental physical characteristics of the semipolar (112¯2) plane GaN film.

Effect of Flux Rate Variation at Fixed V/III Ratio on Semi-Polar (112¯2) GaN: Crystal Quality and Surface Morphology Study

“…Room temperature Raman spectroscopy using z(xx)z scattering configuration was used to examine the effect of the flux rate on the compressive stress of all samples. As shown in Figure 5a, the peaks for (1010) sapphire substrate are found at 378, 416, 741 cm −1 whereas the peaks of A 1 , E 1 and E 2 are responsible for semi-polar GaN epitaxial layer [40]. It is known that the E 2 mode is sensitive to the in-plane stress of the GaN layer; hence, any shifting to a lower or higher value of 568 cm −1 (standard stress-free GaN E 2 peak value) indicates a tensile or compressive strain.…”

Comparative investigation of semipolar (11–22) GaN grown on patterned (113) Si with different V/III ratios via MOCVD

“…Therefore the shift of the E 2 (high) is used to observe the strain on GaN. The standard compressive strain-free GaN E 2 (high) is located at 568 cm −1 , and a shift in the peak of E 2 (high) is proportional to the strain magnitude [46][47][48][49]. The strain of the GaN-on-Si approach in this paper comes from factors such as lattice mismatch and thermal expansion coefficient mismatch, where the lattice mismatch between (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11) Si and (0001) GaN is 17%, which will cause tensile strain on GaN.…”

A comparative investigation of the optical properties of polar and semipolar GaN epi-films grown by metalorganic chemical vapor deposition

“…However, the actual luminous efficiency in the literature is lower than theoretical values due to thin films-related defects and surface roughness [11][12][13]. Growth of (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) GaN on m-plane sapphire has great potential in suppressing the QCSE [14][15][16]. (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) GaN grown on the m-plane substrate could have a near free electric field and a wide growth window.…”

“…Growth of (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) GaN on m-plane sapphire has great potential in suppressing the QCSE [14][15][16]. (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) GaN grown on the m-plane substrate could have a near free electric field and a wide growth window. The latter is important for optimizing the growth of high quality epitaxial thin film materials [17][18][19].…”

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We report on the structural and optical properties of polar gallium nitride on c-plane sapphire substrates and semi-polar (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) GaN films on m-plane sapphire substrates by metalorganic chemical vapor deposition. Polar GaN on c-plane sapphire and semi-polar GaN on m-plane sapphire both show good crystal quality, luminescence, absorption, and Raman characteristics.

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