微小尺寸立方氮化硼晶体蓝紫光发射光谱的测量与分析

Measurement and Analysis of Blue-Violet Light Emitting Spectrum on Tiny Cubic Boron Nitride Crystal

对于微小尺寸的N型宽禁带立方氮化硼（CBN）半导体晶体,在施加恒稳电场的情况下,观察到电致发光现象。通过置CBN单晶样品于光栅单色仪抛物面反射镜焦点的方法,对于CBN的蓝紫光辐射获得了测试系统的最大入射光通量和理想的信噪比。在350~450 nm波长范围内,CBN加上4.7×106V.cm-1恒稳电场条件下,测量出立方氮化硼的蓝紫光发射光谱。同时,结合基于第一性原理的GGA方法计算出的立方氮化硼能带结构和电子态密度,以及测量得到的非线性j-E关系和电击穿特性,讨论了发光机理。提出了在雪崩击穿前的缺陷偶极子极化和击穿后,产生大量的激发态电子,电子在Γ能谷和X能谷间迁移的发光机制。

The electroluminescence effect can be observed by the micro N-type wide-gap CBN semiconductor crystal under the condition of static eletric field. The micro N-type CBN crystal was fixed on the focus of the parabolic reflector of grating monochromator, and the maximum value of transmission ratio and the ideal signal-noise ratio can be obtained. Under the condition of static ectric-field intensity （4. 7 × 10^6 V · cm^-1 ）, the blue-violet light-emitting spectrum of the CBN crystal was measured in the range from 350 to 450 nm. The construction of the CBN energy band, which was calculated with the First-principles method, the nonlinear relationship between current density and the ectric-field intensity that was measured and the phenomenon of electri- cal break-down were considered together to enable us to discuss the luminescence mechanism. Finally, the authors came up with the luminescence mechanism concerning electron migration from Г energy valley to Ⅹ energy valley. The large number of excited electrons we talked about were generated by polarization and breakdown of defect dipole before avalanche breakdown occurred.