超解析近場結構奈米氧化銀薄膜穿透光譜研究

Abstract

在本論文中，首先以光學顯微鏡外接光譜儀與加熱平台，量測單層氧化銀奈米薄膜(AgOx)與超解析近場結構氧化銀(ZnS-SiO2/AgOx/ ZnS-SiO2) 奈米薄膜之聚焦穿透光譜。隨著溫度的增加，在100℃～200℃左右，單層氧化銀5nm薄膜之穿透率由0.8-0.9下降到0.5-0.6，比較AgOx與Ag-rich的n,k值，證實了氧化銀會因熱分解而析出銀結晶顆粒(AgOx→Ag+O2)導致穿透率下降，在單層氧化銀厚度5nm～60nm，相變溫度在135～178℃之間；加熱到600℃，由照片比較可以明顯看出Ag粒子有蒸散的現象。超解析近場結構氧化銀因為上下保護層的作用，中間的氧化銀因熱分解成銀與氧的混合態，故n,k值可以視為銀與氧的混合態，所以穿透率在160℃左右無明顯的下降；在280℃～300℃，隨著中間氧化銀厚度越厚，氧(O2)從邊緣散溢出去，導致Ag比例增加使穿透率下降，加熱到600℃，由照片比較可以明顯看出Ag粒子在中間層有聚合的現象。另外比較平行光室溫穿透光譜，可以明顯看出隨著超解析近場結構氧化銀之氧化銀厚度越厚，其穿透波谷有往長波長方向位移的現象，我們可以利用厚度控制吸收波長的位置。

The spectra of stand alone nano thin film of AgOx nanometer films measured by an optical microscope spectrometer with hearting stage are presented. An obvious change of transmittance of 5nm-thick AgOx nano thin film was found when rose the sample temperature form 100℃ to 200℃. The transmittance decreases from 0.8~0.9 to 0.5~0.6 in this temperature range. Based on the known values of n and k for AgOx and Ag-rich AgOx film, we determine that the decomposed temperature of AgOx increases from 140℃~178℃ with increase film thickness from 5nm to 60nm. Agparticles are evaporated at temperature above 600℃, which were determined by photo-images. The transmittance of super-resolution near-field structure of AgOx was not decrease at 160℃ because ZnS-SiO2 protect against O2 evaporate. This a mixed state of Ag and O2, the n,k index is also mixed by Ag and O2. The transmittance of super-resolution near-field structure of AgOx was decrease at 280℃~300℃ because O2 was evaporated from edge, the rate of Ag increases and transmittance decreases. Ag particle was assembled at 600℃, it is compared by photos. The comparison of transmittance of parallel incident light is used for the measurement at room temperature. The sandwiched structure of AgOx nano thin film displayed a unique transmittance peak for different thickness of the AgOx nano thin film. The transmittance peak can be controlled by the thickness of AgOx nano thin film.