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利用射频磁控溅射方法 ,在n+ Si衬底上淀积SiO2 /Si/SiO2 纳米双势垒单势阱结构 ,其中Si层厚度为 2至 4nm ,间隔为 0 .2nm ,邻近n+ Si衬底的SiO2 层厚度固定为 1.5nm ,另一SiO2 层厚度固定为 3nm .为了对比研究 ,还制备了Si层厚度为零的结构 ,即SiO2 (4.5nm) /n+ Si结构 .在经过 6 0 0℃氮气下退火 30min ,正面蒸上半透明Au膜 ,背面也蒸Au作欧姆接触后 ,所有样品都在反向偏置 (n+ Si的电压高于Au电极的电压 )下发光 ,而在正向偏压下不发光 .在一定的反向偏置下 ,电流和电致发光强度都随Si层厚度的增加而同步振荡 ,位相相同 .所有样品的电致发光谱都可分解为相对高度不等的中心位于 2 .2 6eV(5 5 0nm)和 1.85eV(6 70nm)两个高斯型发光峰 .分析指出该结构电致发光的机制是 :反向偏压下的强电场使Au/ (SiO2 /Si/SiO2 )纳米双势垒 /n+ Si结构发生了雪崩击穿 ,产生大量的电子 空穴对 ,它们在纳米SiO2 层中的发光中心 (缺陷或杂质 )上复合而发光 .
Using RF magnetron sputtering method, SiO2 / Si / SiO2 nano-double-barrier single-potential well structure is deposited on an n + Si substrate, wherein the Si layer has a thickness of 2 to 4 nm and an interval of 0.2 nm, The thickness of the SiO2 layer was fixed at 1.5 nm, and the thickness of the other SiO2 layer was fixed at 3 nm. For the sake of comparative study, a structure with a Si layer thickness of zero (SiO2 (4.5 nm) / n + Si) was also prepared. After annealing for 30 min in nitrogen atmosphere, the translucent Au film was vapor-deposited on the front side and Au was also vapor-deposited on the back side. All the samples were turned on under reverse bias (the voltage of n + Si was higher than the voltage of the Au electrode) Under certain reverse bias, the current and electroluminescence intensity both synchronously oscillate and have the same phase with the increase of Si layer thickness.The electroluminescence spectra of all the samples can be decomposed into relatively high Centered at 2.6eV (550nm) and 1.85eV (670nm) .It is pointed out that the mechanism of electroluminescence of this structure is that the strong electric field under reverse bias makes Au / (SiO2 / Si / SiO2), the avalanche breakdown occurs in the nano-double-barrier / n + Si structure, resulting in a large number of electron-hole pairs. The luminescent center (defect or impurity) in the O2 layer recombines to emit light.