Au/(SiO2/Si/SiO2)纳米双势垒/n+-Si结构的电致发光研究

利用射频磁控溅射方法，在n⁺-Si衬底上淀积SiO₂/Si/SiO_{2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⁺-S i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600℃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2.26eV(550nm)和1.85eV (670nm)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.关键词：电致发光纳米双势垒高斯型发光峰雪崩击穿}

ELECTROLUMINESENCE FROM Au/(SiO2/Si/SiO2) NANOSCALE DOUBLE -BARRIER/n+-Si STRUCTURE

The (SiO₂/Si/SiO₂) nanoscale double-barrier/n⁺- Si structures with Si layers of various thicknesses were fabricated by the two-t arget alternative magnetron sputtering technique. The thicknesses of the Si laye rs in the structures are from 2nm to 4nm with an interval of 0.2nm. The control samples with Si layers of 0nm were also made. After these structures were anneal ed at 600℃ in a N₂ ambient for 30min, electroluminescence (EL) from the Au/SiO₂/Si/SiO₂/n⁺-Si structures were obser ved under reverse biases (n⁺-Si is biased to positive). It was found that the current and EL intensity synchronously swing with increasing Si layer t hickness. All EL spectra of the samples can be decompounded into two Gaussian lu minescent spectra with peaks at 1.85eV (670nm) and 2.26eV (550nm). Analysis of e xperimental results indicates that the EL orginates from the recombination of el ectrons and holes, which are produced in an avalanche process in the Au/(SiO₂/Si/SiO₂) nanoscale double-barrier/n⁺-Si structure , via luminescence centers in the SiO₂ layers.