發光電晶體應用在光邏輯閘電路之設計與開發

Design and Development of Optical Logic Gate with Light-Emitting Transistors

王綺薇(Chi-Wei Wang)

指導教授 ： 吳肇欣

國立臺灣大學/電機資訊學院/光電工程學研究所/碩士(2018年)

https://doi.org/10.6342/NTU201802272

摘要

由於互聯網和數據爆炸的快速增長，摩爾定律逐漸達到其物理極限，且在資訊的傳輸上光通訊相較於傳統銅線具有帶寬高，抗電磁干擾，損耗低的優點，因此，光通訊成為解決日益增長的數據傳輸的一種方法，讓光電積體電路(OptoElectronic Integrated Circuits ,OEICs)成為未來研究發展的重點。在2004年, Prof. Milton Feng和 Prof. Nick Holonyaky在異質雙極性接面電晶體(Heterojunction Bipolar Transistor，HBT）基極加入InGaAs作為量子井發明了發光電晶體(Light-Emitting Transistor, LET)。發光電晶體有著獨特光/電輸出特性，因此可作為光發射器，且具有高速的調變能力。此外，發光電晶體與光電晶體(Heterojunction Phototransistor, HPT)有相似的磊晶結構。當電晶體導通操作在主動模式，基極、集極與次集極接面為逆偏，形成光子吸收層，因此發光電晶體可作為光電晶體作為光偵測器。由上述可知，發光電晶體擁有發光源與光偵測器的特性，成為下一世代光電積體整合電路重要的發展元件之一。
本論文以發光電晶體取代傳統的電晶體作為光邏輯的邏輯單元，設計了電邏輯為NAND gate、光邏輯為AND gate的邏輯閘。在設計前為了確認邏輯閘的操作點，首先分析發光電晶體的直流電特性與光特性。接著，分析以發光電晶體作為光電晶體照光下的直流特性，並以光電晶體的基-集接面作為二極體，量測照光下的特性並分析。接著分析不同尺寸下光電晶體光二極體高頻特性，並利用小訊號模型分析元件受到電容電阻寄生效應的影響。
最後以簡易的達靈頓電路設計邏輯閘，包含一個發光電晶體與一個光電晶體。此邏輯有兩個電輸入和一個光輸入、一個電輸出和一個光的輸出。其中在輸入端是一個電訊號和一個光訊號，另一個電作為邏輯閘開啟電壓。我們成功展示光邏輯閘運作在2kHz與20kHz的結果，光/電輸出訊號互補，電邏輯為NAND gate、光邏輯為AND gate。

關鍵字

發光電晶體 ； 光電晶體 ； PIN光二極體 ； 小訊號模型 ； 光邏輯閘 ； 光電積體整合電路

並列摘要

Owing to the rapid growth of Internet and data explosion, Moore's Law is gradually reaching its physical limit. In addition, in the transmission of data, optical communication has the advantages of high bandwidth, immunity to electromagnetic interference e and low loss compared with conventional copper wires; it has become a method to solve the growing data transmission. Therefore, Optoelectronic Integrated Circuits (OEIC) has become one of the focuses of future research and development. In 2004, Prof. Milton Feng and Prof. Nick Holonyaky invented Light-Emitting Transistor (LET) by incorporating quantum wells (QWs) into the base region of the heterojunction bipolar transistor (HBT). The LET has a unique light/electric output characteristic, so it can be used as a light emitter with high-speed modulation capability. In addition, the LET has a similar epitaxial structure to a Heterojunction Phototransistor (HPT). When the LET is turned on in the active mode, the base, collector and sub-collector junctions are reversed to form a photon absorption layer, so that the LET can function as a HPT. It can be seen from the above that the transistor can be used as a light source and a photodetector, and is one of the important development components of the next generation optoelectronic integrated circuit.
In this thesis, we replace the traditional transistor with the LET as the logic unit of optical logic. By the dual output characteristics of the LET, the logic gate of the electric NAND gate and the optical AND gate is designed. In order to confirm the operating point of the logic gate before design, first, the electrical/optical DC characteristics of the LET are analyzed. Then we use LET as the HPT to analyze the characteristics of HPT under illumination. The characteristics of the illumination are measured and analyzed by using the base-collector junction of the transistor as a diode. Then analyze the high-frequency characteristics of HPT and diodes under different sizes, and use the small signal model to analyze the relationship between the optical modulation frequency and the parasitic capacitance resistance effect.
Finally, the logic gate is designed with a simple Darlington circuit, including a LET and a HPT. This logic has two electrical inputs and one optical input, one electrical output and one optical output. The logic gate input is a signal and an optical signal, and the other electrical input is a DC voltage as a logic gate turn-on voltage. We successfully demonstrated the results of optical logic gate operation at 2 kHz and 20 kHz. The optical/electrical output signals are complementary, the electrical logic is NAND gate, and the optical logic is AND gate.

並列關鍵字

light-emitting transistor ； heterojunction phototransistor ； PIN diode ； small-signal model ； optical logic gate ； OptoElectronic Integrated Circuits

參考文獻

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