Development of Mudulation Spectroscopy for Wide-Gap Semiconductors

本研究的目的是通过对宽禁带半导体能带结构的详细表征，建立对激子条件、杂质条件等进行详细分析的技术。宽禁带半导体材料是近年来备受瞩目的一种材料，并且正在进行针对各种宽禁带材料的激光应用和电子器件应用的研究。在半导体材料的这一新发展中，人们更加期待光学研究对能带结构的详细评估。我们研制了适用于宽禁带半导体评价的新型电子束调制光谱，取得了以下结果：(1)研制了安装在扫描电子显微镜上的电子束调制光谱系统。利用这一特性，我们可以实现从可见光到真空紫外光的调制光谱。此外，在测量期间，EXCI…用我们开发的方法对块体金刚石晶体和金刚石外延膜进行了DID表征。精确的带边结构参数是不够的，因为带隙很大，为5.5 eV，尽管有望用作钻石电子器件。研究了金刚石吸收边的能带结构、能带参数和激子态。(3)将光电子能谱与电子束调制反射信号进行了比较，得到了激子束缚条件和吸收边附近杂质态变化的重要信息。从我们的研究结果中，我们证实了新型电子束调制光谱结合扫描电子显微镜在宽禁带半导体表征中的有效性。此外，它还成功地从光谱分析中获得了与能带参数、激子态、晶格应变、压电场、晶体缺陷等有关的信息，并对这一新技术的实现进行了展望。较少

The purpose of this research is to establish the technique to analyze exciton condition, impurity condition, and so on in detail with characterizing the band structure of the wide-gap semiconductor in detail. Wide gap semiconductor material is remarkable recently, and development proceeds, and the research that it aimed at the laser application and the electron device application with various wide gap material is being done. In this new development of semiconductor material, detailed band structure evaluation by the optical research is being expected all the more. We developed the new electron-beam modulation spectroscopy that was suitable for the wide gap semiconductor evaluation, and got the following result.(1)We developed the electron-beam modulation spectroscopy system mounted on the scanning electron microscope(SEM). By utilizing this tequnique, we can perform the modulation spectroscopy from visible to vacuum ultraviolet light region. Furthermore, during the measurement, an exci … More tation area is evaluated with SEM.(2)Using our developed technique did characterization of bulk diamond crystal and diamond epitaxial films. Precise band-edge structure parameters are not sufficient because that band gap is huge, 5.5 eV, though applications as diamond electron devices are being expected. Here, band structure at the absorption edge of the diamond, band parameters and exciton states have been investigated.(3)Photoemission spectra were compared with electron-beam modulated reflectance signal, and important knowledge could get it about the change in the bound condition of excitons and the impurities states near the absorption edgeFrom our research results, we confirmed that the new type electron-beam modulation spectroscopy combined with SEM was effective in the wide gap semiconductor characterization. Moreover, it succeeded in obtaining the information related to band parameters, exciton states, the lattice strain, the piezo-electric field, the crystal defects, and so on from the spectrum analysis, and an outlook to the realization of this new technique was made. Less