Direct evidence for the amorphous silicon phase in visible photoluminescent porous silicon

Pérez, Jose; Villalobos, José Manuel Berruecos; McNeill, P.; Prasad, J. S.; Cheek, R.; Kelber, Jeffry A.; Estrera, Joseph P.; Stevens, P. D.; Glosser, R.

doi:10.1063/1.107837

Cited by 155 publications

(36 citation statements)

References 13 publications

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“…The result [20] which suggests that a high percentage of this material is, indeed, present in the composition of the n-PS columns [4,21]. The results of this best fit is shown in Fig.…”

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confidence: 71%

Photothermal Characterization of Electrochemical Etching Processed n-Type Porous Silicon

et al. 1997

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The room temperature thermal diffusivity evolution of electrochemically formed porous silicon as a function of the etching time is investigated. The measurements were carried out using the open-cell photoacoustic technique. The experimental data were analyzed using a composite two-layer model. The results obtained strongly support the existing studies, indicating the presence of a high percentage of SiO 2 in the composition of porous silicon material. [S0031-9007(97) PACS numbers: 44.30. + v, 61.43.Gt, 81.05.Cy, 81.05.Rm Since the discovery of its room-temperature visible luminescence [1][2][3][4][5], porous silicon (PS) has become a subject of considerable interest, especially for its promising use as an optoelectronic device [6,7]. There are several methods [8][9][10][11] for fabricating PS from crystalline silicon wafers. The electrochemical etching [1,8] is, however, the most extensively used so far. The morphology of the resulting porous layer is strongly dependent upon the fabrication controlling parameters such as electrolyte composition, current density, etching time, etc., as well as on the type of substrate used.In general, an electrochemically formed n-type PS layer consists essentially of a double-layer system on top of the silicon substrate [1,12]. The outermost thin layer, known as the microporous layer, is typically 10-15 mm thick and is responsible for the observed photoluminescence. Except for very small etching times, the inner layer adjacent to the crystalline substrate, designated as the macroporous layer, consists of a parallel array of airembedded free-standing n-PS columns.Despite the large body of literature that already exists on PS [13,14], so far there has been no reported detailed investigation of the thermophysical properties of this important system. In this Letter we apply the modern photothermal techniques to the evaluation of the thermal properties of electrochemically formed n-PS.The samples used in our experiments were prepared by electrochemical etching on (100) oriented, nondegenerated, n-type ͑2.1 3 10 18 cm 23 ͒ crystalline silicon. The samples had a thickness of roughly 300 mm and an electrical resistivity of 1-5 V cm. The electrochemical etching was carried out following the procedure outlined in Ref. [12]. The crystalline samples, with an appropriate Pt network electrode attached to them, were immersed in a 150 ml Becker filled with HF. A current density of 40 mA͞cm 2 was then applied to the samples using a HP-model 6206B dc power supply operating between 5-10 V. During the etching period the samples were always kept under the irradiation of a 250 W infrared lamp positioned roughly 20 cm away from the etching bath. By controlling the etching time, ranging from 10 to 83 min, we could fabricate samples with different macroporous thicknesses.In Fig. 1 we show the side view optical micrograph of a typical n-PS sample, produced with 60 min etching time. The three distinct regions mentioned above, namely, the microporous and macroporous layers on top of the crystalline sub...

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“…The result [20] which suggests that a high percentage of this material is, indeed, present in the composition of the n-PS columns [4,21]. The results of this best fit is shown in Fig.…”

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confidence: 71%

Photothermal Characterization of Electrochemical Etching Processed n-Type Porous Silicon

et al. 1997

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“…After annealing at 400°C siloxene has an attractive luminescent property similar to porous silicon (Stathis & Kastner , 1987) . d. Structurally disordered phases: A significant amount of amorphous silicon was reported to contain within porous silicon (Perez et al, 1992). It is known that hydrogenated amorphous silicon (a-Si:H) can produce visible PL (Vasquez, 1985) and so it was suggested that a-Si:H might be responsible for 'red' PL band (Vasquez et al 1992) The observed tunability of the PL was further suggested as due to introduction of hydrogen into the amorphous silicon in varying amounts (Cullis & Canham,1991).…”

Section: Photoluminescencementioning

confidence: 99%

Nanocrystalline Porous Silicon

Basu¹,

Kanungo²

2011

Crystalline Silicon - Properties and Uses

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“…Since the initial work of Canham [1] on porous Si prepared by anodization of Si wafers, several workers have reported their experimental results on the fabrication methods [2][3][4], structural characterization [5,6] and optical properties [7][8][9] of nano-and micro-crystals. The PL properties of Si [7,10] and Ge [11] prepared by various methods have also been reported.…”

Section: Introductionmentioning

confidence: 99%