鋁成份漸變極化致發p-型氮化鋁鎵內電洞遷移率隨鋁成份變化行為研究

我們以分子束磊晶技術，在氮化鎵模板上成長了一系列以極化感應產生的p-型氮化鋁鎵，固定鋁含量變化梯度為0.15 %/nm，厚度為100 nm，我們比較在不同鋁含量範圍下其p-型的行為，尤其仔細探討電洞遷移率的變化。鋁含量變化梯度為0.15 %/nm的極化感應p-型氮化鋁鎵能夠產生足量的電洞且能夠表現其平均濃度下的電洞行為。隨著鋁含量增加，電洞濃度一開始緩慢下降，接著開始快速上升，電阻則會持續上升，而電洞遷移率隨著鋁含量增加持續下降，但下降的斜率在平均鋁含量小於40 %左右時較大，平均鋁含量大於40 %左右時下降變為較緩慢。電洞遷移率隨平均鋁含量的變化行為能夠以電洞等效質量和合金散射以及新引入的侷限電荷散射來解釋。

關鍵字

氮化鋁鎵；極化感應；電洞

並列摘要

A series of Al-gradient polarization-induced p-type AlGaN samples of a fixed Al-gradient rate at 0.15 %/nm and a fixed AlGaN thickness at 100 nm are grown with molecular beam epitaxy on GaN templates for comparing their p-type performances. In particular, the variation of hole mobility with the average Al content is carefully investigated. The Al-gradient rate is chosen to be 0.15 %/nm, which is large enough for inducing a significant amount of holes such that its p-type behavior can be measured, but is small enough for such a sample to show the hole behavior at the average Al content. The measured sheet hole concentration decreases slowly first and then increases more dramatically with increasing Al content. The sheet resistance essentially increases monotonically with increasing Al content. The hole mobility decreases monotonically with increasing Al content. The decreasing slope is larger (smaller) when the Al content is lower (higher) than ~40 %. The variation behavior of hole mobility is successfully interpreted based on the Al-content dependent effective hole mass and alloy scattering, and a newly introduced mechanism of bound-charge scattering.

並列關鍵字

p-AlGaN ； polarization induced ； graded AlGaN

參考文獻

References

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國際替代計量

鋁成份漸變極化致發p-型氮化鋁鎵內電洞遷移率隨鋁成份變化行為研究

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