Porous SiGe Nanostructures Formed by Electrochemical Etching of Thin Poly-SiGe Films
Porous SiGe Nanostructures Formed by Electrochemical Etching of Thin Poly-SiGe Films
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DOI：
10.1149/1.1695531
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发表时间：
2004-05
影响因子：
3.9
通讯作者：
T. D. Caño;L. F. Sanz;P. Martin;M. Avella;J. Jiménez;Andrés Rodríguez;J. Sangrador;T. Rodríguez;V. Torres-Costa;R. Martín-Palma;J. M. Martínez-Duart
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文献类型：
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作者：
T. D. Caño;L. F. Sanz;P. Martin;M. Avella;J. Jiménez;Andrés Rodríguez;J. Sangrador;T. Rodríguez;V. Torres-Costa;R. Martín-Palma;J. M. Martínez-Duart
我们研究了电流密度(J)和刻蚀时间对电化学刻蚀形成多孔多晶硅(PP-SiGe)层的影响，其中Ge组分在0~0.55范围内。起始材料为非故意掺杂的多晶SiGe薄膜，通过低压化学气相沉积以非晶态沉积，然后晶化。发现PP-Si结构在很大程度上是均匀的，并且在低J值时显示出约5 nm的纳米晶。Pp-SiGe结构在结构上表现出不均匀，低J时纳米晶尺寸约为10 nm，高J值和增加刻蚀次数时纳米晶尺寸减小，达到2-4 nm。对于低到中等的J值，pp-SiGe薄膜的成分显示出轻微的Ge富集。对于高J值，在x=0.38的样品中，所有的Si都被刻蚀，多孔层的成分是纯Ge。对于高Ge组分(x=0.55)的样品，这种效应不是很强。主要的辐射复合机制不是激子机制，我们将其与多孔膜晶体结构中的缺陷或纳米晶/自然SiO_2界面的状态相联系。
We have studied the effect of the current density (J) and etching time in the formation of porous poly-SiGe (pp-SiGe) layers, with Ge fractions in the 0 to 0.55 range, by electrochemical etching. The starting material was unintentionally doped polycrystalline SiGe thin films, deposited in amorphous state by low-pressure chemical vapor deposition and subsequently crystallized. pp-Si structures were found to be homogeneous at large scale and show nanocrystalline of around 5 nm for low J values. The pp-SiGe structures show nonuniformities in their structure; the nanocrystal size is around 10 nm for low J and decreases for high J values and increasing etching times, reaching values of 2-4 nm. The composition of the pp-SiGe films, for low to moderate J values, shows a slight Ge enrichment. For high J values, in samples with x = 0.38, all the Si was etched and the composition of the porous layer is pure Ge. This effect is not so strong for samples with high Ge fractions (x = 0.55). The dominant radiative recombination mechanism is not excitonic; we associate it with recombination via defects in the crystalline structure of the porous film or states at the interface nanocrystals/native SiO 2 .