Blue electroluminescence device by MOS structure with Si-implanted SiO_2

由于硅是超大规模集成电路（VLSI）最重要的材料，与Si VLSI优越的工艺兼容性使得Si基发光器件在集成智能显示的各种应用中具有吸引力。研究了硅掺杂Si0_2的MOS结构蓝色电致发光器件。采用Au/ITO电极，在p型或n型Si衬底上制备了栅极氧化物中SiO_2中含有过量Si的MOS结构。除了注入外，还采用了硅离子掺杂技术将多余的硅引入栅极氧化物中。分析了器件的电特性和电致发光特性。无论硅衬底类型如何，高硅剂量的测试器件在大V_G区域产生较大的电流。电容对栅极电压（C-V）特性呈现迟滞曲线。结果表明，硅注入诱导的陷阱中的电荷随外加电压的极性而改变。掺硅氧化物的MOS结构没有出现迟滞曲线。通过透射电镜观察，Si衬底的损伤表面产生了较大的泄漏电流。SIMS分析表明，SiF_<3^+>和SiF_<2^+>等光离子种类的数量多于预期，导致离子谱更深。在直流（dc）操作下，两种Si衬底中SiO_2掺杂的MOS结构在450 nm处有一个峰值。两种衬底类型的MOS结构的EL光谱均可分为5个分量，即hv=1.0、1.6、1.9、2.4、2.8 eV。提出了硅掺杂MOS电致发光器件的电致发光机理模型。在交流（ac）操作下的EL光谱与直流EL具有相同的成分。在交流操作中，EL光谱中较低的光子能量分量变大。这可以解释为离子注入引起的栅极氧化物的陷阱能级响应速度的差异。

Since silicon is the most important material for very large scale integrated circuits (VLSI), superior process compatibility with Si VLSI makes Si-based light emitting devices attractive for the wide variety of application of integrated intelligent displays. Blue electroluminescence (EL) devices by MOS structure with Si-implanted Si0_2 were studied. MOS structures of which gate oxide had excess Si in SiO_2 were fabricated on p- or n-type Si substrates with Au/ITO electrodes. In addition to implantation, Si ion doping technique was used to introduce excess Si into the gate oxide. Electric and EL characteristics of the devices were analyzed.Test devices with higher Si dose gave larger current in large V_G region regardless of the type of Si substrate. Capacitance vs. gate voltage (C-V) characteristics showed hysteresis curves. It suggests that charges in the traps induced by Si-implantation are altered with the polarity of applied voltages. MOS structures with Si ion doped oxide did not give hysteresis curves. The damaged surfaces of Si substrates, which were observed by cross section TEM, caused large leakage current. SIMS analysis suggests that the amount of light ion species such as SiF_<3^+> and SiF_<2^+> was more than the expected, resulting in deeper ion profile.EL spectra under direct-current (dc) operation showed a peak at 450 nm in MOS structures with Si-implanted SiO_2 of both Si substrate types. EL spectra of MOS structures with either substrate type can be separated into 5 components i.e.hv=1.0,1.6,1.9,2.4,2.8 eV. A model of EL emission mechanism is proposed for the Si-implanted MOS EL device. EL spectra under alternating current (ac) operation have the same components as dc-EL. The lower photon energy components of EL spectra become larger in ac operation. It can be interpreted as the difference of response speed of trap levels induced into the gate oxide by ion implantation.