矽鍺電制吸收元件之量子侷限史塔克效應

Quantum Confined Stark Effect (QCSE) in Silicon-Germanium (SiGe) Electro-Absorption Devices

張哲瑋(Che-Wei Chang)

指導教授 ： 郭宇軒

國立臺灣大學/電機資訊學院/電子工程學研究所/碩士(2008年)

https://doi.org/10.6342/NTU.2008.10187

摘要

現今中、長程通訊，光已經取代了電的地位，在短程通訊光也逐漸取代電的傳輸，但在晶片連結中，仍以電訊號作為主流。自從半導體技術的進步，元件尺寸逐漸縮小，導線電阻增加，而晶片內部連結延遲時間逐漸縮小，因此主要是晶片與晶片之間的連線速度掌握了整個系統的速度，光連線是解決現今矽晶片之間與晶片內部高速通訊瓶頸之必要方案之一，有機會成為未來高速、高容量資訊通訊技術之關鍵。

高速外加光調變器(external modulator)為現今光通訊之重要元件。電制吸收光調變器由於在應用上具備有高速調變、低驅動電壓，非常適合外部調變的高頻寬光通訊系統。量子侷限史塔克效應(Quantum confined Stark effect; QCSE) 為最有效之光調變器原理之一，矽基材料上矽鍺量子井已被證實存在量子侷限史塔克效應。

本論文將探討矽鍺寬量子井上之量子侷限史塔克效應。因矽鍺為非直接能隙之材料，除直接能隙之吸收外，亦可在更低能量處發現非直接能隙之吸收，此部分將導致背景吸收。為量測矽鍺量子井之電制吸收元件，搭建電制吸收效應之量測系統，研究厚量子井設計所獲之量子侷限史塔克效應以及直接能隙吸收和非直接能隙吸收對於吸收頻譜之影響，厚量子井有不若薄量子井之吸收係數、激子效應以及較低之非直接能隙吸收。此外，利用穿隧共振法進行數值模擬與探討。

關鍵字

量子侷限史塔克效應 ； 光調變器 ； 矽鍺量子井 ； 電制吸收 ； 光電元件

並列摘要

Optical communications have dominated the intermediate to long distance data transmission and also gradually replaced the metal interconnects for the short-distance links. The decreasing device size in silicon chips increases the interconnect resistance and hence degrades the system speed severely, thus the optical interconnects is one of the solutions to enable high-speed and high-capacity chip-scale communication technology.

The high-speed external optical modulator is one of the key components routinely used in today’s optical communications. The Quantum confined stark effect (QCSE) – one of the most effective modulator operating theorems – can enable high-speed external modulation with low operation voltage. The QCSE had been demonstrated in the germanium quantum well system grown on silicon and would enable optical interconnects integrated with silicon chips.

The QCSE at room temperature with thick quantum well was investigated in this thesis study. Since both silicon and germanium are indirect bandgap materials, there exist not only direct gap absorption transition but also indirect gap absorption with lower transition energy which leads to the background absorption. An electro-absorption measurement system was setup to study the QCSE as well as the direct and indirect absorption. The thick quantum well structure exhibits electroabsorption effect in the C-band and has lower quantum well energy, weaker exciton, and less indirect absorption. Besides, the simulations based on the tunneling resonance method are discussed.

並列關鍵字

QCSE ； Optical modulator ； SiGe quantum well ； Electroabsorption

參考文獻

[1] The International Technology Roadmap for Semiconductors (ITRS).

[3] C. Kurth, "SSB/FDM Utilizing TDM Digital Filters," IEEE Trans. on Commun., vol.19, no.1, pp. 63-71, Feb. 1971.

[4] R. Essiambre, B. Mikkelsen, G. Raybon, "Intra-channel cross-phase modulation and four-wave mixing in high-speed TDM systems," Elec. Lett., vol.35, no.18, pp.1576-1578, 2 Sep. 1999.

[5] K. Liou, K. K. Dreyer, E. C. Burrows, J. L. Zyskind, J. W. Sulhoff, "A 24-channel WDM transmitter for access systems using a loop-back spectrally sliced light-emitting diode," IEEE Photo. Tech. Lett., vol.10, no.2, pp.270-272, Feb. 1998.

[6] Y. Suzaki, H. Yasaka, H. Mawatari, K. Yoshino, Y. Kawaguchi, S. Oku, R. Iga, H. Okamoto, "Beyond 80-Gbit/s-throughput monolithically integrated eight-channel WDM modulator module for multi-channel optical transmitter," Opt. Fiber Commu. Con., vol.1, pp. 23-27, Feb. 2004.