| 학회 | 한국재료학회 |
| 학술대회 | 2017년 가을 (11/15 ~ 11/17, 경주 현대호텔) |
| 권호 | 23권 2호 |
| 발표분야 | A. 전자/반도체 재료 분과 |
| 제목 | Linearly Polarized Photoluminescence of Anisotropically Strained c-plane GaN Grown on Stripe-Shaped Cavity-Engineered Sapphire Substrate |
| 초록 | Anisotropic strain in lll-nitride semiconductor materials provides potentials to study new characteristics that are not observed in isotropically strained materials. The effects of anisotropic strain in GaN on optical, acoustic, and vibrational properties have been reported [1]. One of the interesting effects from the anisotropically strained materials is modification of valence band structure and resultant linearly polarized emission [2]. However, c-plane GaN grown on c-plane sapphire substrate, a typical growth scheme, exhibits unpolarized emission due to isotropic in-plane strain. We realized polarized photoluminescence (PL) of c-plane GaN on c-plane sapphire substrate by using a stripe-shaped cavity-engineered sapphire substrate (SCES), which is expected to induce anisotropic in-plane strain in the GaN grown on SCES. The fabrication process of SCES and GaN growth on SCES were described in detail elsewhere [3]. In order to investigate the anisotropic strain in GaN on SCES, high resolution X-ray reciprocal space mapping (RSM) around symmetric and assymetric reflections was conducted. The GaN on SCES was under anisotropic strain of -0.014% and -0.134% along the direction perpendicular (x) and parallel (y) to the stripe direction, respectively. To measure the polarized PL from the sample, a linear polarizer was placed between sample and CCD detector and rotated from 0 to 90 o in steps of 10 o. The PL peak shift of -13 meV and 1.45 times higher PL intensity was observed along the direction of electric field (E) parallel to stripe direction compared to E perpendicular to stripe direction. The experimental results were compared with theoretical value based on k∙p perturbation theory. It was found that the anisotropic PL was attributed to anisotropic in-plane strain. In this presentation, mechanism for the anisotropic strain of GaN on SCES and the modification of the band structures will be discussed. References [1] A. Alemu et al., Phys. Rev. B 57, 3761 (1998). [2] P. P. Paskov et al., J. Appl. Phys. 234, 892 (2002). [3] D. Moon et al., J. Cryst. Growth 441, 52 (2016). |
| 저자 | 김종명1, 이승민1, 양두영1, 장정환1, 이동현1, 박용조2, 윤의준1 |
| 소속 | 1서울대, 2차세대융합기술(연) |
| 키워드 | GaN; Anisotropic strain; Polairzed photoluminescence; theoretical calculation |
