Liu Hai-Bo, Jia Gang, Chen Gang, Meng Qing-Ju, Zhang Tie-Chen
State Key Laboratory of Integrated Optical-Electronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China.
Guang Pu Xue Yu Guang Pu Fen Xi. 2008 Jul;28(7):1569-72.
UV absorption spectroscopy of artificial cubic boron nitride (cBN) single crystal flake, synthesized under high-temperature and high-pressure, was studied in the present paper. UV WINLAB spectrometer was used in the experiments, and MOLECULAR SPECTROSCOPY software was used for data analysis. The UV-cBN limit of 198 nm was showed in this test by a special fixture quartz sample. We calculated the energy gap by virtue of the formula: lambda0 = 1.24/E(g) (microm). The energy gap is 6. 26 eV. There are many viewpoints about the gap of cBN. By using the first-principles theory to calculate energy band structure and density of electronic states of cBN, an indirect transition due to electronics in valence band jumping into conduction band by absorbing photon can be confirmed. That leads to UV absorption. The method of calculation was based on the quantum mechanics of CASTEP in the commercial software package of Cerius2 in the Co. Accerlrys in the United States. The theory of CASTEP is based on local density approximation or gradient corrected LDA. The crystal parameter of cBN was input to the quantum mechanics of CASTEP in order to construct the crystal parameter model of cBN. We calculated the energy gap of cBN by the method of gradient corrected LDA. The method underestimates the value of nonconductor by about 1 to 2 eV. We gaot some opinions as follows: cBN is indirect band semiconductor. The energy gap is 4.76 eV, less than our experiment. The reason may be defect that we ignored in calculating process. It was reported that the results by first principles method of calculation of the band generally was less than the experimental results. This paper shows good UV characteristics of cBN because of the good agreement of experimental results with the cBN band width. That is a kind of development prospect of UV photo-electronic devices and high-temperature semiconductor devices.
本文研究了在高温高压下合成的人工立方氮化硼（cBN）单晶薄片的紫外吸收光谱。实验中使用了UV WINLAB光谱仪，并使用MOLECULAR SPECTROSCOPY软件进行数据分析。通过特殊的夹具石英样品，在本次测试中显示出198 nm的紫外 - cBN极限。我们根据公式：lambda0 = 1.24/E(g)（微米）计算能隙。能隙为6.26 eV。关于cBN的能隙有许多观点。通过使用第一性原理理论计算cBN的能带结构和电子态密度，可以确认价带中的电子通过吸收光子跃迁到导带而导致的间接跃迁。这导致了紫外吸收。计算方法基于美国Accerlrys公司Cerius2商业软件包中CASTEP的量子力学。CASTEP理论基于局域密度近似或梯度校正LDA。将cBN的晶体参数输入到CASTEP的量子力学中，以构建cBN的晶体参数模型。我们通过梯度校正LDA方法计算了cBN的能隙。该方法对非导体值的低估约为1至2 eV。我们得到了以下一些观点：cBN是间接带半导体。能隙为4.76 eV，小于我们的实验值。原因可能是我们在计算过程中忽略的缺陷。据报道，通过第一性原理计算能带的结果通常小于实验结果。由于实验结果与cBN带宽的良好一致性，本文展示了cBN良好的紫外特性。这是紫外光电器件和高温半导体器件的一种发展前景。
