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

• Main Authors: Che-Wei Chang, 張哲瑋
• Other Authors: Yu-Hsuan Kuo
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/68912652674397154480

碩士 === 國立臺灣大學 === 電子工程學研究所 === 96 === 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.