| Summary: | 碩士 === 國立臺灣大學 === 光電工程學研究所 === 104 === Possessing the transistor property and high-speed optical modulation characteristics, light-emitting transistors (LETs) and transistor lasers (TLs) have become one of the suitable candidates for next-generation optoelectronic integrated circuit (OEIC) device and optical communication light source. In the thesis, the theoretical model including direct-current (DC) and alternating-current (AC) characteristics of the TL is proposed. To describe the lasing characteristics in the TL, we discuss the effect of the Franz-Keldysh (F-K) absorption using the modified rate equations. Different threshold currents and slopes of the light-versus-current (LI) curves under different voltage biases can be observed in experiments and these phenomena can be described clearly from this model. For AC characteristics, the TL provides not only current modulation but direct voltage-controlled modulation scheme of optical signals via FK photon-assisted tunneling effect. A complete model composed of the intrinsic optical transfer function and an electrical transfer function is proposed to explain the behaviors of voltage modulation. Moreover, we discuss the small-signal frequency chirping under voltage modulation of the TL. The decreasing frequency chirping effect for small-signal high-speed modulation is demonstrated.
In addition, we fabricate the first quantum-well-embedded blue LET. The electrical and optical characteristics of the blue LET are demonstrated in this work. The center wavelength of the electroluminescence (EL) spectrum is about 435 nm. The visible wavelength shows that it has great potential for visible light communication system.
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