Study on the polarity control of hexagonal-structure widegap compound semiconductors and its effect on the material control

六方结构宽禁带化合物半导体极性控制及其对材料控制的影响研究

基本信息

批准号：
13450121
负责人：
YOSHIKAWA Akihiko
金额：
$ 9.6万
依托单位：
Chiba University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2004
项目状态：
已结题

项目摘要

Widegap compound semiconductors such as GaN have the hexagonal wurtzite structure and are lack in symmetry along the c-axis. Reflecting this property, the epitaxy process itself and many properties of these materials were greatly affected by the polarity/direction during growth. However, the mechanism for the polarity selection and its control during growth of these materials were not clear.In this research, first we investigated the polarity control mechanism in both MOVPE and MBE of GaN, and we proposed a successful method for the polarity inversion from N-polarity to Ga-polarity, where Al-bilayer played an important role. It was found that the All-covered surface was chemically/thermally stable and Al-bilayer could be frozen into the crystal during growth.Next, the polarity control of ZnO was investigated. The polarity control of oxides was complicated compared to that of nitrides. This was partly attributed to the fact that oxides tended to be amorphous, in particular at low temperatures, the ZnO buffer deposited at low-temperatures sometimes could not keep the epitaxy relationship between the substrate and epilayer. We proposed to use nitrides as buffer layers resulting in successful polarity control.Finally we extended our work to the InN epitaxy for the first time and we clarified that the N-polarity growth regime was preferable in the epitaxy of InN itself and its material control as well. This was because the InN easily decomposes at such low temperatures below 500 C but the epitaxy temperature for the N-polarity growth could be as high as 600 C, which was about 100 deg higher than that of In-polarity growth. On the basis of these results, we succeeded in growth of device-quality InN, InN-based ternary alloys, such as InGaN and InAlN, and very fine structure SQW/MQW consisted of InN/InGaN and InN/InAlN heterostructures for the first time.

GAN等广宽化合物半导体具有六角形的Wurtzite结构，并且沿C轴缺乏对称性。反映这一特性，外观过程本身以及这些材料的许多特性在生长过程中受极性/方向的影响很大。然而，这些材料生长期间极性选择及其控制的机制尚不清楚。在这项研究中，首先，我们研究了GAN的Movpe和MBE的极性控制机制，我们提出了一种成功的极性反演的方法n极性对GA极性，al-bilayer发挥了重要作用。发现全包覆盖的表面是化学/热稳定的，并且可以在生长过程中将al-bilayer冻结到晶体中。对ZnO的极性控制进行了研究。与硝酸盐的极性控制相比，氧化物的极性控制变得复杂。这部分归因于以下事实：氧化物往往是无定形的，尤其是在低温下，沉积在低温下的ZnO缓冲液有时无法保持底物与粘胶之间的外交关系。我们提议将氮化物用作缓冲层，从而成功进行极性控制。在本文中，我们首次将工作扩展到旅馆的外观，我们澄清说，在Inn本身的外观及其物质控制中，N-Polarity的增长制度是优选的出色地。这是因为Inn在低于500 C的低温下很容易分解，但是N极性生长的外在温度可能高达600 C，比偏置生长高约100度。根据这些结果，我们成功地成功地增长了设备质量旅馆，基于Inn的三元合金，例如Ingan和Inaln，以及非常精细的结构SQW/MQW，首次由Inn/Ingan和Innn Onn-Onnal Onsostructures组成。