新型酞菁的光致发光性质研究

研究了2,3-四-(2-异丙基一5-甲基苯氧基)氢酞菁在10,77,177和300 K下石英衬底上的浇铸膜和单晶硅衬底上真空镀膜(约200 nm厚)在300 K下光致发光光谱.氢酞菁的浇铸膜光致发光光谱在上述温度下均出现荧光发射和磷光发射峰,在177和300 K下出现了1 673 nm激基缔合物峰.该峰的出现与分子抗聚集能力的强弱有关,在300 K激基缔合物峰比在177 K下的峰强,从氢酞菁分子结构特点讨论了形成激基缔合物的原因.随着温度的升高,可以观察到荧光发射峰渐渐减弱而激基缔合物峰变强.由于浇铸膜和真空镀膜的酞菁分子聚集态不同导致了斯托克司位移的差异,真空镀膜的发光峰峰值在1 140 nm左右,与酞菁浇铸膜的峰值差别较大.浇铸膜的发光峰的半高宽为300 nm,而真空镀膜发光峰的半高宽为100 nm左右.     

Charge storage characteristics of nonvolatile memories with chemically-synthesized and vacuum-deposited gold nanoparticles

Carrier injection and charge loss characteristics of nonvolatile memories with chemically-synthesized (CS) and vacuum-deposited (VD) gold nanoparticles (Au-NPs) have been investigated. Compared to CS counterparts, the memories with VD Au-NPs exhibit a higher dot density of 3.77 × 10¹¹ cm⁻², leading to a larger memory window. Further, the energy from valence-band edge to vacuum level (E_{VB_vac}) of tunneling oxide for the samples with CS and VD Au-NPs is found to be 9.04 and 9.85 eV respectively. The small E_{VB_vac} value of the memories with CS Au-NPs is resulted from the formation of a thin chemical oxide (SiO_x) on thermally-grown SiO₂ tunneling layer during the chemically synthesized process, contributing to a slow erasing behavior. Besides, the programming of the memories with VD Au-NPs is saturated at high gate bias, which has been well-explained by the electrons induced potential coupling between Au-NPs. Superior data retention property and high temperature dependence of charge loss are observed for the memories with CS Au-NPs, which can be ascribed to the thick tunneling oxide layer by the additional SiO_x film.