Polarity dependence of In-rich InGaN ternary alloys and InN/InGaN MQWs
- PDF / 399,398 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 35 Downloads / 160 Views
0892-FF06-03.1
Polarity dependence of In-rich InGaN ternary alloys and InN/InGaN MQWs S. B. Che1,2,3, T.Shinada1, T.Mizuno1, Y. Ishitani1,2,3, and A. Yoshikawa1,2,3 1 Department of Electronics and Mechanical Engineering, 2Center for Frontier Electronics and Photonics, and 3InN-project as a CREST program of JST, Chiba University 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
ABSTRACT In-rich InGaN films (XIn>0.5) and InN/InGaN multi-quantum wells were grown on Ga- and N-polarity GaN templates by radio-frequency plasma-assisted molecular beam epitaxy. The In-polarity InGaN films grown at 450oC showed superior crystalline quality and smoother surface morphology compared to the N-polarity samples, which were grown at 500~550oC. By using the In-polarity In0.7Ga0.3N as a barrier layer, the InN/InGaN multi-quantum wells were successfully fabricated on the III-element polarity GaN templates at 450oC. Fine periodic structures and strong photoluminescence emission around optical communication wavelength were obtained from the In-polarity MQWs. These results indicate that high quality InGaN films and the InN/InGaN MQWs can be obtained in the In-polarity growth regime in spite of its lower growth temperature.
INTRODUCTION InN is attracting strong interest in its unique properties such narrow bandgap energy as 0.6~0.7eV [1-6]. This indicates the potential application of InN-based III nitrides in near-infrared photonic devices that operate at optical-communication wavelengths, such as ultra-high-speed optical modulators and near-infrared light emitters operating at high temperatures. An InN/InGaN multi-quantum wells (MQWs) structure is a candidate for an active layer of the photonic devices. At present, there are a few reports about the fabrication of the InN-based MQWs, in which near-infrared emission at around 1.55µm were observed by photoluminescence (PL) measurement [7-11]. However, compared to InGaN/GaN MQWs, which are generally used as an active layer for bule-LEDs and LDs, crystalline quality of the InN-based MQWs is still poor and its drastic improvement is necessary when considering the realistic InN-based optical devices. It is well known that the polarity control is an important factor in the III-nitride epitaxy due to its great influence on structural and surface properties. Generally, in the GaN and InGaN with smaller In composition (XIn < 0.36) [12], high-quality and smooth surface morphology can be obtained in the III-polarity growth compared to the N-polarity growth. On the other hand, in the case of InN epitaxy, we already reported that the higher-side growable temperature of InN is about 600oC in N-polarity, which is about 100 oC higher than that in In-polarity [5]. The higher-growth temperature would be an advantage for high-quality epitaxial growth and hetero-epitaxial growth with other III-nitrides. In fact, we have successfully fabricated the InN/InGaN and InN/AlInN MQWs in N-polarity growth [10,11]. However, In-polarity InN growth was recently reported by a few research groups and they confirmed that co
Data Loading...
