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|標題:||A Study of the Characteristics of Platinum Oxide Thin Films for Use in Super-Resolution Near-Field Structure Disc
|關鍵字:||氧化鉑;Platinum Oxide;超解析近場光碟;super-resolution near-field structure disc||出版社:||材料工程學研究所||摘要:||
應用於超解析近場結構光碟時，不同氧流量比製備的PtOx遮罩層對碟片的讀寫機制並沒有太大的影響。寫入時，在高功率雷射脈衝的照射下，PtOx遮罩層薄膜會受熱分解成奈米級的Pt顆粒與O2。O2被釋放後因氣體壓力會在ZnS-SiO2保護層間產生一剛性氣泡訊號坑，並造成上下保護層的永久變形；而熱分解產生的Pt金屬顆粒則均勻的分佈在氣泡坑內。讀取時，在雷射光照射下，剛性氣泡訊號坑內的奈米級Pt金屬顆粒產生表面電漿子訊號增強效果，而使得讀取訊號大幅提升。在紅光雷射寫入功率為15 mW與讀出功率4.0 mW下，記錄點大小為150 nm時，三種氧流量比製備的碟片，CNR值均可超過40 dB。不過，由於氧流量比愈低，被介電層保護的PtOx的熱分解溫度也愈低，造成碟片的讀取穩定度會隨著氧流量比的降低而降低。
In this study, we have investigated the constituent phases and thermal decomposition behavior of the reactively sputtered PtOx films, prepared at various flow ratios of O2/(O2+Ar), with and without ZnS-SiO2 protective layers. The structural phase changes of the PtOx films sandwiched between ZnS-SiO2 protective layers after irradiation by pulsed lasers with various power have also been examined. In Addition, the dependence of the super-resolution near-field properties during readout on the constituent phases of PtOx mask layer was tested by an optical disk drive tester. Based on the experimental observations, recording and readout mechanisms of the super-RENS disks with PtOx mask layers were proposed.
It was found that the constituent phases of the as-deposited PtOx gradually transferred from a mixture amorphous Pt and PtO, to a pure amorphous PtO phase, then to a mixture of amorphous PtO and PtO2, as the oxygen flow ratio of O2/(O2+Ar) was increased. After thermal annealing, the reduction of PtO2 into PtO and decomposition of PtO into Pt and O2 took place. The thermal decomposition of PtOx with and without ZnS-SiO2 dielectric protective layer was confirmed to be an irreversible process. For the unprotected PtOx films, both the thermal decomposition temperature and active energy were found to decrease with increasing the oxygen flow ratio, while for the PtOx films protected by ZnS-SiO2 dielectric layers, the thermal decomposition temperature and activation energy increased with increasing the oxygen flow ratio.
As used in the Super- Resolution Near-Field structure (super-RENS) disk, the effect of the oxygen flow ratios or the constituent phases of the PtOx mask layer on the recording and readout mechanisms was not appreciable. During the recording process, nano-sized Pt particles and O2 gas are generated in the center region of the laser spot through the thermal decomposition of PtOx. After O2 is released, rigid bubble pits are formed in the PtOx mask layer, and permanent deformations are also created in the upper and lower ZnS-SiO2 protective layers due to the O2 gas pressure. The Pt particles with size of tens of nanometers are uniformly distributed in the rigid bubble pits. During the readout process, the interaction between Pt particles and incident laser yields a strong localized surface plasmon at the Pt particles, leading to a significantly high electric-field enhancement. As a result, the readout signal intensity is greatly improved. The carrier-to-ratios (CNRs) of over 40 dB for mark length of 150 nm were obtained by an optical disk drive system with a wavelength of 635 nm and a numerical aperture of 0.6 in all disks with PtOx mask layers prepared at different oxygen flow ratio. The writing power was set at 15 mW and readout power was set at 4.0 mW. Apparently, the oxygen flow ratio or the constituent phase of the PtOx mask layer has minimal effect on the super-resolution near-field property. However, the readout stability of the Super-RENS disk did decrease with decreasing the oxygen flow ratio due to the low thermal decomposition temperature of the PtOx mask layer prepared at a low oxygen flow ratio.
|Appears in Collections:||材料科學與工程學系|
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