Fabrication of III-V semiconductor/Si heterojunctions without disturbance of inter-diffusion toward high frequency devices

含硅异质结的形成为先进硅器件开辟了一条新途径。尽管III-V型半导体的带隙变化很大，但由于界面处的混合，III-V型半导体与Si之间的异质结表现出复杂的掺杂谱。由于N原子在Si中不具有电活性，iii族氮化物和Si之间的界面预计会显示出简单的传导型结构。在iii族氮化物中，InN的带隙约为1.9 eV，与Si的带隙接近，是硅异质结的理想候选材料。在本研究中，利用射频等离子体（13.56 MHz）中氮气产生的金属In和氮自由基，在500℃的衬底温度下在Si（001）衬底上生长了InN。InN生长层表面呈镜面状。通过x射线光发射光谱（XPS）测量证实了In和N在生长层中的掺入。在厚度为0.3 μm的Si上生长的层在RHEED中显示出一个定向环状图案，x射线衍射峰归属于InN。因此，本研究生长了多晶InN。测得生长层的带隙为1.96 eV。在没有掺杂的情况下，InN生长层表现为n^+型。InN的霍尔迁移率和载流子浓度分别为28 cm^2/Vs和3 × 10^<20> cm^<-3>。在n型Si（001）衬底上生长的极薄InN上，通过XPS分析确定了InN/Si异质结的带偏。测量到的带偏为1.49 eV，表明InN/Si异质结是一种很有前途的系统，可以在Si器件中实现对空穴的阻挡。

Formation of heterojunctions including Si opens a new path toward advanced Si devices. Although III-V semiconductors have a wide variation in terms of their bandgap, heterojunctions between III-V semiconductors and Si show a complicated doping profile due to an intermixing at the interface. Since N atoms are not electrically active in Si, the interface between a group-III nitride and Si is expected to show a simple configuration of the conduction type. Among group-III nitrides, InN with a bandgap of around 1.9 eV, which is close to the bandgap of Si, is a promising candidate for the Si heterojunction. In this study, InN was grown on Si(001) substrates at a substrate temperature of 500℃ by molecular beam epitaxy (MBE) using metal In and nitrogen radicals generated from nitrogen gas in rf plasma (13.56 MHz). The surface of the InN grown layer showed a mirror surface. Incorporations of In and N in the grown layer were confirmed by X-ray photoemission spectroscopy (XPS) measurement. The grown layer on Si with a thickness of 0.3 μm showed an oriented ring pattern in RHEED, and an X-ray diffraction peak ascribed to InN.Thereby, polycrystalline InN was grown in this study. The bandgap of the grown layer was measured to be 1.96 eV.The InN grown layer showed n^+-type without an intentional doping. The Hall mobility and the carrier concentration of InN were evaluated to be 28 cm^2/Vs and 3 × 10^<20> cm^<-3>, respectively. The band-offset of the InN/Si heterojunction was determined by XPS analysis on a very thin InN grown on n-type Si(001) substrate. The band-offset was measured to be 1.49 eV, indicating that the InN/Si heterojunction is a promising system to realize a barrier against holes in Si devices.