銻磷砷化銦/砷化銦塊材光激發螢光特性研究

本實驗室已經成功利用氣態源分子束磊晶機成長出一系列銻磷砷化銦塊材在n+-(100)指向的砷化銦基板上。隨著樣品成分的變化，樣品表面型態與磊晶晶格排列品質也會隨著遠離長晶溫度(470℃)之混溶隙區域而逐漸改善。我們針對這一系列樣品進行光激發螢光頻譜(Photoluminescence)之分析與討論，根據樣品成分在混溶隙內部與外部，將樣品區分為三種情況討論。深入混溶隙內部的樣品，如C1898~C1900，其低溫PL由帶尾能態(band-tail state)放光所主導，而放光峰值隨著溫度上昇而紅移，另一方面，其高溫PL頻譜具有較大的半寬且其變化量正比於溫度的平方根，這些樣品高溫部分的頻譜均呈現高斯分布和PL峰值能量不隨溫度改變等現象，我們可以利用組態座標模型(configuration-coordinate model)解釋其為一深階能階放光。相反地，對於遠離混溶隙的樣品，其變溫PL具有“inverse S-shape”特徵，因帶尾能態(band-tail state)的發光在溫度昇高時載子會填到較高能階而造成放光峰值呈現先紅移再藍移的現象，在高溫時其PL峰值能量與理論計算的結果相近，且峰值能量隨溫度變化量遵守Varshni law；利用能階密度與費米-迪拉克分佈函數乘積來模擬帶間躍遷的PL頻譜並與實驗結果比較，可以說明在遠離混溶隙的樣品，在高溫是由帶間躍遷(band-to-band)所主導。至於成分落入混溶隙內部邊緣的樣品例如C1767，其低溫PL是由帶尾發光所主導，而在接近室溫時可以在高能量端發現一微弱訊號，其PL峰值能量與理論計算結果相近，可以推測在高溫時C1767同時存在深階能階與帶間躍遷。最後討論成分在混溶隙內部與外部的樣品之活化能，其樣品低溫PL由帶尾主導發光的部份，擬合出低溫活化能與其解離的溫度吻合，至於成分在混溶隙內部的樣品高溫活化能可以利用組態座標模型(configuration-coordinate model) 來解釋PL光譜強度的衰減情形。

關鍵字

氣態源分子束磊晶；混溶隙；光激發螢光；組態座標模型

並列摘要

We have successfully grown InAsPSb samples on n+ (100) InAs substrates by gas-source molecular beam epitaxy. Samples with rich arsenic composition which are located away from miscibility gap in quaternary composition plane show better surface morphology and crystal quality. Power dependent and temperature dependent photoluminescence measurements were performed on these samples. Because of the existence of miscibility gap, PL results of these samples can be roughly classified as three different groups. For sample C1898-C1900, whose compositions lie inside the miscibility gap, low temperature PL transition was dominated by band-tail state recombination; on the other hand, the high temperature PL spectra show wide FWHM values and the FWHM values increase proportionally to the root of temperature. Gaussian shape spectra and temperature independent PL peak energy behavior imply deep level transition which can be explained by configuration-coordinate model. With sample’s compositions outside the miscibility gap, temperature dependent PL has “inverse S-shape” behavior which due to the tail-states resulted from alloy fluctuation. The PL peak energy follows Varshni law and is close to calculated bandgap value as temperature increasing. Theoretically calculated band to band PL emission spectrum fits well with experimental results suggest a band-edge recombination with samples grown outside miscibility gap at high temperature. Finally, for samples with composition near miscibility gap boundary, we can observe weak peak signal located at the high energy side whose energy was quite close to calculated results at room temperature. We conjectured that the deep level transition and band to band transition exist in high temperature. At last we attribute the low temperature activation energy to the delocalization energy of tail-states. For the sample’s compositions inside miscibility gap, the high temperature activation energy can be explained by configuration-coordinate model.

並列關鍵字

gas-source molecular beam epitaxy ； miscibility gap ； Photoluminescence ； configuration-coordinate model

參考文獻

[1] J. Wagner, C. H. Mann, M. Rattunde, and G. Weimann, “Infrared semiconductor lasers for sensing and diagnostics,” Appl. Phys., A, vol. 78, pp. 505-512, 2004.

[2] A. Krier and Y. Mao, “2.5μm light-emitting diodes in InAs0.36Sb0.20P0.44/InAs for HF detection,” IEE. Proc. Optoelectron, vol. 144, pp. 355-359, 1997.

[4] Z. M. Fang, K. Y. Ma, D. H. Jaw, R. M. Cohen, and G. B. Stringfellow, “Photoluminescence of InSb, InAs, and InAsSb grown by organometallic vapor phase epitaxy,” J. Appl. Phys., vol. 67, pp. 7034-7039, 1990.

[5] E. H. Reihlen, M. J. Jou, Z. M. Fang, and G. B. Stringfellow, “Optical absorption and emission of InP1-xSbx alloys,” J. Appl. Phys., vol. 68, pp. 4604-4609, 1990.

[6] E. R. Gertner, D. T. Cheung, A. M. Andrews, and J. T. Longo, “Liqid phase epitaxtal growth of InAsxSbyP1-x-y layers on InAs,” J. Electron. Mater., vol. 6, pp. 163-170, 1977.

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銻磷砷化銦/砷化銦塊材光激發螢光特性研究

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