研討鋅擴散及其應用於量子井異質結構 成分混和之影響

Study of Zn diffusion and its application for compositional mixing in quantum well heterostructures

傅安教

指導教授 ： 謝光前 ； 吳孟奇

國立清華大學/電機資訊學院/電子工程研究所/碩士(2013年)

摘要

本論文主要探討鋅擴散對砷化鎵/砷化鋁鎵結構發生impurity induce layer disordering(IILD)現象的影響。我們利用封管技術製作出砷化鋅(ZnAs2)合成物當作擴散源，並且利用電漿輔助化學氣相沉積法沉積氮化矽，藉由可調變的製程參數將氮化矽的折射率調變到接近Si3N4 的 2~2.05，利用氮化矽折射率在此範圍下結構緻密的特性來當作擴散的阻擋層，阻擋鋅擴散和 IILD 的現象發生。並在鋅擴散後，可以完整維持結構晶格的品質。
我們利用封管技術做所有的鋅擴散實驗，一開始先針對砷化鎵單層結構做不同溫度和時間的鋅擴散，在考慮到控制擴散深度的情形下，從中選取600℃作為擴散溫度。接著對不同鋁含量的砷化鋁鎵單層結構和砷化鎵/砷化鋁鎵結構做鋅擴散的研究。在PL量測下，我們成功地在600℃擴散條件下，使砷化鎵/砷化鋁鎵結構發生impurity induce layer disordering(IILD)及成分均質化的現象，並且有效地藉由控制擴散時間達成不同的混和程度。

關鍵字

鋅擴散

並列摘要

In this study, we used the sealed-quartz-ampoules to produce ZnAs2 as our diffusion source to perform Zn diffusion, and optimized the deposition process by varying parameters to deposit silicon nitride films and adjust the refractive indices to be in the range of 2.0 to 2.05, utilizing its characteristics of having a denser and less permeable structure than SiO2 to inhibit the Zn diffusion and IILD.
We used sealed quartz ampoules to do all diffusion experiments. At first, we did the Zn diffusion into n+GaAs (Si doped~1018cm-3) substrates with ZnAs2 as the diffusion source at different diffusion temperatures for various times. Among three temperatures, we chose 600℃ to perform our Zn diffusion studies for different Al contents of AlxGa1-xAl (~2um) layer on GaAs substrate and Al1-xGaxAs / GaAs structures. We have demonstrated layer disordering in two Al1-xGaxAs/GaAs structures, Sample A and B. The disordering was induced by Zn diffusion with ZnAs2 as the diffusion source. The PL data show that we can effectively control the extent of disordering by varying the diffusion time at 600℃. Moreover, we can use a SiNx as diffusion mask to effectively inhibit Zn diffusion to preserve the crystal "quality" and keep the active layer during Zn diffusion as sharp as the as-grown one.

參考文獻

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