| 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 | Growth and characterization of Ga-doped a-plane ZnO films on r-plane sapphire substrates by plasma-assisted molecular beam epitaxy |
| 초록 | Recently, researches on the growth of nonpolar ZnO films have been received much attention because nonpolar direction in wurtzite crystal system plays an important role by providing an environment free from polarization-related electric fields. Several studies have been reported on basic properties of nonpolar a-plane ZnO on r-plane sapphire substrates grown by various techniques. However, very few studies on doping into nonpolar ZnO films have been reported and most of studies on doped ZnO films have been performed for polar ZnO films on c-plane sapphire. It is well known that the group III elements such as Al, Ga and In are easier to control a carrier concentration in ZnO because they have lower vapor pressure comparing with the group VII elements such as Cl, Br and I. Among the group III elements, Ga is well known to act as an effective n-type donor in ZnO due to similarity of the ionic radius and the covalent radius of Ga (0.62 and 1.26Å, respectively), which are similar to those of Zn (0.74 Å, 1.31 Å). In this study, we report on structural, optical, and electrical properties of Ga-doped a-plane (11-20) ZnO films grown on r-plane sapphire substrates by plasma-assisted molecular beam epitaxy. The carrier concentration of Ga-doped ZnO films were controlled from 7.2×1018 cm-3 to 3.6×1020 cm-3. The typical striated surface morphology normally observed from a-plane ZnO films disappeared with Ga doping. The crystal quality addressed by FWHM values of (11-20) XRC showed the initial decrease but it showed the dramatic increase for the sample with high Ga doping, which resulted from a development of polycrystalline feature. As doping the Ga, more tensile in-plane stress is developed and a red-shift of peak positions in room temperature photoluminescence spectra. Photoluminescence spectra from the Ga-doped single crystalline ZnO films showed dominant near band edge emission with negligibly weak deep level emission. Without the degradation of properties resulted from polycrystalline feature with rotated domains, the maximum Ga dopability of around 3.6 × 1020 cm-3 was observed in a-plane ZnO film. |
| 저자 | 한석규1, 이효성1, 홍순구1, 윤나라2, 오동철2, 안병준3, 송정훈3, Takafumi Yao4 |
| 소속 | 1충남대, 2호서대, 3공주대, 4Tohoku Univ. Center for Interdisciplinary Research |
| 키워드 | Semiconductiong II–VI materials; Oxides; Doping; Molecular beam epitaxy |
