Palacios-Huerta L, Cabañas-Tay S A, Luna-López J A, Aceves-Mijares M, Coyopol A, Morales-Sánchez A
CIDS-BUAP, Apdo. 1651, Puebla, Pue. 72000, México.
Nanotechnology. 2015 Oct 2;26(39):395202. doi: 10.1088/0957-4484/26/39/395202. Epub 2015 Sep 11.
In this paper, we study the structural, optical and electro-optical properties of silicon rich oxide (SRO) films, with 6.2 (SRO₃₀) and 7.3 at.% (SRO₂₀) of silicon excess thermally annealed at different temperatures and used as an active layer in light emitting capacitors (LECs). A typical photoluminescence (PL) red-shift is observed as the silicon content and annealing temperature are increased. Nevertheless, when SRO₃₀ films are used in LECs, a resistance switching (RS) behavior from a high current state (HCS) to a low conduction state (LCS) is observed, enhancing the intense blue electroluminescence (EL). This RS produces a long spectral blue-shift (∼227 nm) between the EL and PL band, and it is related to structural defects created by a high current flow through preferential conductive paths breaking off Si-Si bonds from very small silicon nanoparticles (Si-nps) (Eδ (Si ↑ Si ≡ Si) centers). LECs with SRO₂₀ films do not present the RS behavior and only exhibit a slight shift between PL and EL, both in red spectra. The carrier transport in these LEC devices is analyzed as being trap assisted tunnelling and Poole-Frenkel through a quasi 'continuum' of defect traps and quantum dots for the conduction mechanism in SRO₃₀ and SRO₂₀ films, respectively. The results prove the feasibility of obtaining light emitting devices by using simple panel structures with Si-nps embedded in the dielectric layer.
在本文中，我们研究了富硅氧化物（SRO）薄膜的结构、光学和电光特性。该薄膜含有6.2（SRO₃₀）和7.3原子百分比（SRO₂₀）的过量硅，在不同温度下进行热退火，并用作发光电容器（LEC）的有源层。随着硅含量和退火温度的增加，观察到典型的光致发光（PL）红移。然而，当SRO₃₀薄膜用于LEC时，观察到从高电流状态（HCS）到低传导状态（LCS）的电阻切换（RS）行为，增强了强烈的蓝色电致发光（EL）。这种RS在EL和PL带之间产生了长光谱蓝移（约227 nm），并且它与高电流通过优先导电路径产生的结构缺陷有关，该优先导电路径会破坏非常小的硅纳米颗粒（Si-nps）（Eδ（Si↑Si≡Si）中心）中的Si-Si键。具有SRO₂₀薄膜的LEC不存在RS行为，并且在红色光谱中PL和EL之间仅表现出轻微的偏移。对于SRO₃₀和SRO₂₀薄膜中的传导机制，分别通过缺陷陷阱和量子点的准“连续体”将这些LEC器件中的载流子传输分析为陷阱辅助隧穿和普尔-弗伦克尔效应。结果证明了通过使用在介电层中嵌入Si-nps的简单面板结构来获得发光器件的可行性。
