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標題: | 不同尺寸設計對發光電晶體光頻寬之影響 The effect of optical bandwidth of light-emitting transistors under different size layout design |
作者: | Peng-Hao Chou 周鵬豪 |
指導教授: | 吳肇欣(Chao-Hsin Wu) |
關鍵字: | 異質接面雙極性電晶體,發光電晶體,等效小訊號電路模型,光頻率響應, Heterojunction bipolar transistor,Light-emitting transistor,Equivalent small-signal circuit model,Optical response, |
出版年 : | 2013 |
學位: | 碩士 |
摘要: | 自2004年起,發光電晶體的發明打破了以往對載子復合放光速度的認知,傳統發光二極體及二極體雷射其載子復合的生命週期是在奈秒等級(Nano-second level),而發光電晶體已經被實驗證實其自發性復合放光的生命週期可達到皮秒等級(Pico-second level),其快速的載子復合速度,加上本身就是電晶體的許多特性,使得發光電晶體及電晶體雷射成為下一代光通訊系統光源的候選人之一。
為了提升元件自發性放光的調變速率(降低載子復合的生命週期),縮小尺寸成為了一個重要的課題。在本篇論文中,我們設計了不同射極以及不同基極大小的In0.49Ga0.51P/GaAs 發光電晶體元件,藉此研究之間的關係。透過直流量測與分析,我們發現不同結構下的元件其電流增益(β = IC/IB)和光輸出會因為電路造成的寄生效應和不同的載子復合過程而有所差異。當固定基極,將射極半徑從9 μm (E18B27)縮減至6.5 μm (E13B27)時,電流增益會因為有較高的電流密度而增加,且光輸出較易被侷限在元件內部;當固定射極,將基極半徑從13.5 μm (E13B27)縮減至11 μm (E13B22)時,電流增益也會有所提升。透過高頻小訊號的量測,我們可以得到GHz等級的自發性放光調變速度,且利用發光電晶體之等效電路小訊號模型得到元件的電路特性。 我們發現到元件的表現會受到電路的電阻電容寄生效應影響,並且可以透過去嵌入(De-embed)的方式將電路造成的效應去除,進而得到元件的本質光頻寬(Intrinsic optical bandwidth),而本質光頻寬會隨著基極電流密度的提升而增加。我們透過對現有元件的分析去預測E8B27、E8B16及E5B16的光頻寬,當IB為2 mA時,E5B16的本質光頻寬可以達到14 GHz,但是受到電路效應的影響後,整體光頻寬(Overall optical bandwidth)會降至8.1 GHz,而8.1 GHz依然有機會可以突破過去實驗得到的光頻寬。 The invention of light-emitting transistors (LETs) in 2004 has revolutionized the concept of the carrier radiative recombination rate for the past 50 years. It is recognized that the radiative recombination lifetime of the traditional light-emitting diodes (LEDs) and diode lasers (DLs) are in the nano-second range. However, the pico-second level of recombination lifetime of LETs and transistor lasers (TLs), which can be determined by experiments, provides great potential for next generation optical communication light source. In the thesis, we have designed different sizes of emitter radius hE and base radius hB of InGaP/GaAs LETs in aperture layout design. Through different layout designs, the LETs exhibit different electrical current gain (β = IC/IB) and optical light output due to different carrier recombination processes in the transistor base region and different parasitics. By reducing the lateral emitter radius from 9 to 6.5 μm, β increases due to the higher injection current densities and better confinement of the radiative recombination in the base region. Moreover, β increases when reducing the base radius from 13.5 to 11 μm with fixed emitter diameter. We have obtained multi-GHz spontaneous light modulation of LETs from rf measurement, and the device performance is closely related to different layout designs with different device parasitics under equivalent circuit small-signal model analysis. The intrinsic optical bandwidth, enhanced under the higher base current density, can be also obtained by de-embeding the circuit parasitics effect. Through the analysis of small-signal equivalent circuit models, we have projected the overall optical bandwidth under device lateral scaling, such as E8B27, E8B16, and E5B16. As IB is 2 mA, the intrinsic optical bandwidth of E5B16 is 14 GHz. By the circuit paracistics effect, the overall optical bandwidth would drop to 8.1 GHz, but it still has a great potential to break the record. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/61977 |
全文授權: | 有償授權 |
顯示於系所單位: | 光電工程學研究所 |
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