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利用双光束分光光度计对高温退火前后的掺氮和未掺杂6H-SiC晶体的透射及反射谱进行了分析,发现无论退火前后,两种SiC晶体在紫外区均存在强烈的吸收。在可见和近红外区,尤其是未掺杂SiC样品具有很高的透射率,退火后,两种样品的透射率均明显提高。利用荧光分光光度计研究了退火前后样品的光致发光特性,结果表明:在390 nm Xe灯激发下,两种样品在417 nm和436 nm处均可观察到蓝光发射,417 nm处的发光归结于C簇的发光,436 nm处的发光机理为从晶粒的核心激发载流子转移到晶粒表面,并与其上的发光中心辐射复合;同时,掺氮SiC在575 nm处还存在发光峰,为氮掺入后引起的非晶SiC的发光,在325 nm Xe灯激发下,525 nm处存在发光峰,其详细发光机制有待进一步研究。
The transmission and reflection spectra of nitrogen-doped and undoped 6H-SiC crystals before and after high-temperature annealing were analyzed by using a dual-beam spectrophotometer. It was found that there was a strong absorption of both SiC crystals in the UV region before and after annealing. In the visible and near-infrared regions, especially for undoped SiC samples, which have high transmissivity, the transmissivity of both samples was significantly improved after annealing. Fluorescence spectrophotometer was used to study the photoluminescence characteristics of the samples before and after annealing. The results showed that blue light emission was observed at 417 nm and 436 nm both at the excitation of 390 nm Xe lamp, and luminescence at 417 nm In C cluster, the emission mechanism at 436 nm shifted from the core of the crystal to the surface of the crystal and radiated with the luminescent center on the surface of the crystal. At the same time, the luminescence peak at 575 nm , Which is the luminescence of amorphous SiC caused by the incorporation of nitrogen. The luminescence peak exists at 525 nm under the excitation of 325 nm Xe lamp. The detailed luminescence mechanism remains to be further studied.