鍺錫二極體之研製與元件特性分析

Fabrication and Study of Si-based GeSn p-i-n Photodiode

游育豪(Yu-Hao You)

指導教授 ： 張國恩

國立中正大學/工學院/機械工程學系/碩士(2015年)

摘要

在追逐更快更低耗能且更有效率之電腦運算的今日，挑戰更極限的最小電路線寬是目前的作法，但一種更有前景的矽光積體電路也已經開始蓬勃發展。矽光積體電路以光作為傳遞訊號的方式，有著低損耗、高頻寬與製程整合容易等特點，其中以雷射光源、光調變器、光波導和光偵測器來組成光通訊系統，因此研究與發展更高性能的光通訊用光電元件已是產學界的熱門話題。

本研究致力於改良波導式的p-i-n光二極體元件，以鍺錫合金為材料，探討其作為光偵測器時的暗電流問題，及預測各錫含量鍺錫合金波導元件所需要的最短長度。在本文中主要分為元件的製程改良、光吸收理論模擬、新的元件結構設計與製作，暗電流量測與分析。本理論模擬結果顯示本文所採用的3.85%鍺錫合金僅需20-25μm長即可完全吸收入射光子；在元件的製作上，本研究成功地製作出50μm長之鍺錫波導式二極體，暗電流的量測結果顯示，在-1V時的暗電流密度為0.06 A/cm2，有效改善前代元件的高暗電流問題。此外本研究亦探討在不同溫度下之暗電流特性，可觀察到當溫度上升到390K時，元件在偏壓-2V時的暗電流密度來到11.63 A/cm2，比室溫時的0.26 A/cm2大了45倍。藉由變溫暗電流的量測數據可以擬合出元件的活化能，並以活化能判斷元件屬於間接再復合機制，同時透過加速因子的計算進行可靠度分析，本文之研究成果得以了解鍺錫二極體之電性已開發高性能的鍺錫二極體光電元件。

關鍵字

二極體 ； 波導 ； 鍺錫合金 ； 暗電流

並列摘要

Reducing the physical size of electronic devices has been an effective way to improve the performance of integrated circuits. On the other hand, silicon photonics is considered a potential solution for enhancing the performance of integrated circuits due to the advantages of low loss, low energy consumption and high transmission bandwidth. To construct silicon photonics platform, it is necessary to develop light sources, modulators, waveguides and detectors on silicon wafers.

In this research, we fabricate Si-based GeSn p-i-n waveguide photodiodes with reduced current density. By shortening the length of waveguide to 50μm , the dark current decreases significantly compared to the our first-generation devices with long waveguide as 2mm. Temperature-dependence dark current measurements were performed, and the results show that the dark current density grows with increasing temperature. At -2V bias, the dark current density at 390k is 11.63 A/cm2, 45 times larger than that at room temperature. Activation energy was extracted by analyzing the temperature-dependent dark currents this photodiode, confirming that the recombination mechanism is trap-assisted recombination. Finally, the activation energy can be used to calculate acceleration factor which relate to reliability analysis. The present investigation on dark currents could be helpful to develop high-performance photonic devices based on GeSn p-i-n diodes.

並列關鍵字

dark current ； photodiode ； waveguide ； GeSn

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