| 학회 | 한국재료학회 |
| 학술대회 | 2010년 가을 (11/11 ~ 11/12, 무주리조트) |
| 권호 | 16권 2호 |
| 발표분야 | F. Display and optic Materials and processing(디스플레이 및 광 재료) |
| 제목 | Study on properties of MgxZn1-xO films grown on r-plane sapphire substrates by plasma-assisted molecular beam epitaxy |
| 초록 | ZnO has received considerable attention due to its potential applicability to optoelectronic devices such as ultraviolet-light emitting diodes (UVLEDs) and laser diodes (LDs). As well known, however, polar ZnO with the growth direction along the c-axis has spontaneous and piezoelectric polarizations that will result in decreased quantum efficiency. Recently, nonpolar ZnO has been studied to avoid such a polarization effect. To realize the optoelectronic device operating, ternary nonpolar compounds as barrier materials are necessary to make quantum well structures. Therefore, growth of high quality ternary compounds for quantum well structure is one of the important tasks that should be solved. MgXZn1-XO is one of most promising alloys for this application because the alloy of ZnO with MgO provides a wide range of band-gap engineering spanning from 3.3 to 7.8 eV. In fact, many studies have reported that Mg is favorable for growth of ternary compounds with ZnO due to the large band gap of MgO (7.8 eV) and the similarity of ionic radius between Zn (0.60Å) and Mg (0.57Å). However, very few studies on growth of nonpolar MgXZn1-XO film have been performed. In this study, we report on the structural and optical properties of non polar a-plane MgxZn1-xO (0≤x≤0.57) films on r-plane sapphire substrates grown by plasma-assisted molecular beam epitaxy. Reflection high energy electron diffraction (RHEED) revealed a formation of cubic MgZnO phase when an Mg concentration increases. Although the cubic phase was not detected from the RHEED patterns, room temperature (RT) photoluminescence (PL) and transmission electron microscopy consistently revealed the formation of cubic MgZnO phase from the Mg0.21Zn0.79O film. The Mg0.11Zn0.89O film showed a band edge emission at ~360nm, which is a shorter wavelength than the ZnO (~373 nm), from the RT PL measurements. Photoluminescence excitation (PLE) measurements at RT showed that band-gap energies of MgxZn1-xO films could be tuned up to ~4.65eV (~270nm) although cubic MgZnO phase were mixed for high Mg concentration. For the single phase wurtzite MgZnO film, band-gap energy of 3.48eV was obtained from the Mg0.11Zn0.89O film. |
| 저자 | 한석규1, 이효성1, 홍순구1, 안병준2, 송정훈2, 정명호3, 이주호3, 이정용3, Takafumi Yao4 |
| 소속 | 1충남대, 2공주대, 3KAIST 신소재공학과, 4Tohoku Univ. |
| 키워드 | Semiconductiong II–VI materials; Oxides; Zinc compounds; Molecular beam epitaxy |
