以矽基板製作矽微碟共振腔及其時間解析之研究

Fabrication and Time-Resolved Studies of Silicon Microdisk Resonators from a Silicon Substrate

陳石原(Shih-Yuan Chen)

指導教授 ： 毛明華

國立臺灣大學/電機資訊學院/電子工程學研究所/碩士(2017年)

https://doi.org/10.6342/NTU201702292

摘要

我們以(100)單晶矽基板為材料製作矽微碟共振腔並當作光開關元件，以U型錐形光纖耦合的方式進行量測，以中心波長1330nm之寬頻光源SLD (Super Luminescent Diode)進行傳輸頻譜量測，驗證微碟共振腔的共振特性及確定迴音廊模態位置；並利用激發、探測量測法(Pump-Probe Measurement)與時間解析傳輸量測法(Time Resolved Transmission Measurement)來分析載子生命期和開關時間，並以此結果探討矽微碟共振腔作為光開關元件的合適性。
以往製作矽微碟時，矽微碟下方通常有一層微米等級厚的二氧化矽埋藏層，故一般使用SOI (silicon on insulator)基板，或以濕式氧化方式成長一層二氧化矽層後，再接續成長非晶矽層的方式來製作矽微碟[1]，兩者皆利用一層二氧化矽埋藏層來提供高蝕刻選擇比及折射率對比。在此我們提出並展示了一個新的矽微碟製程方法，前後兩次成長二氧化矽薄膜做出微碟上方及側向阻擋層，再利用KOH濕式蝕刻對矽各晶向蝕刻速率不同的特性，可直接於矽基板上製作單晶矽微碟共振腔及支持柱的結構，最後透過爐管1000℃濕氧化減少圓周表面粗糙度，完成直徑10微米的微碟。在傳輸頻譜量測下，觀察到一階及其他高階徑向模態產生，其中一階模態Q值可達8600，並將該元件應用於全光開關上。

關鍵字

矽微碟 ； 光開關 ； U型錐形光纖 ； 光學量測 ； 激發-探測

並列摘要

We fabricated silicon microdisk resonators from a single-crystal silicon (100) substrate and applied it as an optical switch. We used a U-shaped tapered fiber coupling method for the transmission measurement with a super luminescent diode as the light source whose center wavelength is 1330nm. This measurement can be used to verify the resonance properties of the fabricated microdisks and to determine the characteristic modal structure of whispering-gallery modes. Furthermore, we used pump-probe measurement and time-resolved transmission measurement to analyze carrier lifetime and switching time of our devices. Based on these experimental results, the appropriateness of silicon microdisks as optical switching devices will be discussed.
For the fabrication of Si microdisks, there is usually a buried oxide layer of around one micron in thickness. An SOI substrate or an amorphous silicon layer on a thick oxide layer prepared by wet oxidation is the common choice for this purpose [1]. Both structures provide a high etch selectivity and a large refractive index contrast. In this study, we proposed and demonstrated a new process technology for Si microdisks. First, we fabricated SiO2 protection layers at the top and side of Si microdisks respectively by depositing SiO2 thin film twice. After this step, we used KOH wet etching to form the single-crystal Si microdisks and their pedestal structures due to the anisotropic etching rate in different lattice directions. Finally, we used the 1000ᵒC wet oxidation process to reduce surface roughness of 10μm microdisk resonators. From the transmission spectra, we can observe first and other high order radial modes. The highest quality factor is 8600. These microdisk devices have been applied to optical switches.

並列關鍵字

Si microdisk ； optical switching ； U-shaped Tapered fiber ； Optical measurement ； Pump probe measurement

參考文獻

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