Near-infrared free carrier absorption in heavily doped silicon

Baker-Finch, Simeon C.; McIntosh, Keith R.; Yan, Donghang; Fong, Kean Chern; Kho, Teng

doi:10.1063/1.4893176

Cited by 148 publications

(80 citation statements)

References 36 publications

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“…The slight difference in the initial UV range spectra is due to minor differences in the nanostructures caused by the diffusion process. The low reflectance of the low-resistivity samples in the infrared range (wavelengths beyond 1000 nm) is caused by free-carrier absorption [35].…”

Section: Surface Morphology and Reflectancementioning

confidence: 99%

Impact of Standard Cleaning on Electrical and Optical Properties of Phosphorus-Doped Black Silicon

Pasanen

Laine

Vähänissi

et al. 2018

IEEE J. Photovoltaics

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Abstract-Black silicon (b-Si) has been estimated to considerably grow its market share as a front texture of high-efficiency silicon solar cells. In addition to excellent optical properties, high-efficiency cell process requires extreme cleanliness of the bulk material, and thus cleaning of b-Si surfaces is often a critical process step. While standard clean (SC) 1 solution efficiently removes possible contamination from wafer surfaces, we show here that it may cause challenges in b-Si solar cells. First, the silicon etch rate in SC1 solution is shown to depend on the phosphorous concentration and as high rate as ∼1.4 nm/min is observed on planar emitter surfaces. When extending the study to b-Si, which has much larger surface area in contact with the cleaning solution, even higher volumetric Si consumption occurs. This is observed in significant changes in emitter doping profiles, for instance, a 10 and 30-min cleaning increases the sheet resistance from 47 to 57 Ω/ and 127 Ω/ , respectively. Furthermore, the SC1 solution alters substantially the nanostructure morphology, which impacts the optics by nearly doubling and more than tripling the surface reflectance after a 30 and 60-min immersion, respectively. Thus, uncontrolled cleaning times may impair both the electrical and optical properties of b-Si solar cells.

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Section: Surface Morphology and Reflectancementioning

confidence: 99%

Impact of Standard Cleaning on Electrical and Optical Properties of Phosphorus-Doped Black Silicon

Pasanen

Laine

Vähänissi

et al. 2018

IEEE J. Photovoltaics

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“…In general, the wavelength of photons is shorter than 1100 nm to meet the requirement of interband absorption 11,17 for generating electron-hole pairs modifying the formation rate of the porous silicon layer. Because the onset is at 1100 nm where interband absorption is weak enough to result in FCA contributing to the total absorption of silicon, 18 we used a 1310 nm laser to achieve the FCA effect on a silicon substrate, as shown in the experiment schematic illustrated in Figure 1a. The anodization was performed in a darkroom to compare directly the etching results between the irradiated region and the dark region under the same conditions.…”

mentioning

confidence: 99%

Communication—Effect of Free-Carrier Absorption on an Anodized Silicon Surface for Producing Dense and Uniform Nanocrystals

Lee

Chiang

2018

J. Electrochem. Soc.

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The present study disclosed that free-carrier absorption (FCA) activated by 1310-nm laser irradiation caused a distinct effect on the formation of nanocrystals in the porous layer of p ++ silicon with the anodization less than 10 minutes. Under ultraviolet excitation, the photoluminescence peak locations are quite different in the irradiated spot (∼535 nm) and in the normal porous silicon (∼640 nm). In the irradiated spot, the intensity of the photoluminescence is at least 10 times higher than that of the peripheral porous silicon layer. This shows that the FCA effect provides an alternative way to produce dense and uniform nanocrystals. Electrochemical processing 1 has been the most common way to produce nanostructures, e.g., as a porous silicon layer, in a silicon substrate for many unique applications. [2][3][4][5] In the structure of porous silicon, the diameter of the pore walls in tens of nanometers sharp nanocrystals with one-or two-dimensional quantum confinement [6][7][8] that can be used for constructing devices of silicon lighting.By adopting the anodization model of porous silicon formation in a hydrofluoric acid (HF)-based electrolyte, 6 we obtain the following:Obviously, holes play a dominant role in the dissolution of silicon, which allows us to modify the porous structure directly by adjusting the current density, dopant/electrolyte concentration, and processing time. Controlling the number of holes by applying an appropriate illumination, 9-11 the silicon atoms that dissolved on the bulk surface immersed in electrolyte could create a three-dimensional coralline-like structure filled with nanocrystals during anodization. These nanocrystals display the characteristics of quantum confinement with the behavior of photoluminescence for detection. Here, we demonstrate that the free-carrier absorption (FCA) produced by irradiation with a long-wavelength laser (>1100 nm) can modify the formation of p-type porous silicon in anodization.The materials used were boron-doped and phosphorus-doped (100) silicon prime wafers (cut into 5 × 5 cm 2 ) with two resistivities: 1 to 10 cm (p-and n-specimens) and 0.001 to 0.005 cm (p ++ and n ++ specimens). Prior to anodization, all silicon specimens were cleaned using solutions of NH 4 OH:H 2 O 2 :H 2 O = 1:1:5 and HCl:H 2 O 2 :H 2 O = 1:1:6, and then dipped into 1% HF for several seconds to remove native surface oxide. Electrochemical anodization was performed at a constant current density of 10 mA/cm 2 with a platinum cathode in the electrolyte (a mixture of 49.5% HF and 99.5% ethanol at 1:1 volume ratio). During anodization, we used a laser system equipped with a 1310 nm laser drive (max power = 7.0 mW) to create a 1.0-mm diameter light spot on the surface of the specimens.In the anodization of n-type silicon, illumination that produces photogenerated holes 12,13 is a way to carry out electrochemical etching. However, for p-type silicon, the effect of illumination is the opposite: inhibiting the formation of porous silicon 5,9,10,14 because of photogenerated electr...

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“…This can result in a λ-dependence of that varies between λ 1.5 and λ 3.5 (rather than the λ 2 predicted by Drude theory) in the limits of phonon or ionized impurity scattering, respectively. [11] In general, several scattering modes coexist, with the dominant mode depending on the impurity concentration and species. It is usually reasonable to expect the exponent r in the dependence λ r to increase with doping.…”

Section: Free Carrier Absorption (Fca) Vs Interband Absorption (Iba)mentioning

confidence: 99%

“…The calculations assume that first, band-to-band absorption is negligible, and second, the free-carrier concentration equals the majoritycarrier concentration in equilibrium. The model for the free carrier absorption coefficient is derived from Baker-Finch [11] derivation which measures and models reflectance and transmittance dispersion to arrive at a parameterisation for the free carrier absorption coefficient that applies in the wavelength range between 1000 and 1500 nm, and the range Front and back side laser injection methods were explored in this chapter, and bulk Si resistivity and its effect on free carrier absorption were discussed here. It will be shown later in chapter 6 how the bulk resistivity effects the absorption processes in Si.…”

Section: Measurements Of Absorption Coefficient Of High and Low Resismentioning

confidence: 99%

“…Free carrier absorption is usually identified as a parasitic process it has a negative impact on the performance of devices such as silicon solar cells, thermophotovoltaic cells, and infrared photodetectors. [11] Free-carrier absorption (FCA) is the result of direct absorption of photons by the carriers in the conduction or valence band. These transitions are shown in figure 2.1 as process (D) and process (E), respectively, in the valence band (free holes) and conduction band (free electrons).…”

Section: Free Carrier Absorption (Intraband Absorption)mentioning

confidence: 99%

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Laser as a Tool to Study Radiation Effects in CMOS

Ajdari¹

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Energetic particles from cosmic ray or terrestrial sources can strike sensitive areas of CMOS devices and cause soft errors. Understanding the effects of such interactions is crucial as the device technology advances, and chip reliability has become more important than ever. Particle accelerator testing has been the standard method to characterize the sensitivity of chips to single event upsets (SEUs). However, because of their costs and availability limitations, other techniques have been explored. Pulsed laser has been a successful tool for characterization of SEU behavior, but to this day, laser has not been recognized as a comparable method to beam testing. In this thesis, I propose a methodology of correlating laser soft error rate (SER) to particle beam gathered data. Additionally, results are presented showing a temperature dependence of SER and the "neighbor effect" phenomenon where due to the close proximity of devices a "weakening effect" in the ON state can be observed.ii Acknowledgments

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Near-infrared free carrier absorption in heavily doped silicon

Cited by 148 publications

References 36 publications

Impact of Standard Cleaning on Electrical and Optical Properties of Phosphorus-Doped Black Silicon

Impact of Standard Cleaning on Electrical and Optical Properties of Phosphorus-Doped Black Silicon

Communication—Effect of Free-Carrier Absorption on an Anodized Silicon Surface for Producing Dense and Uniform Nanocrystals

Laser as a Tool to Study Radiation Effects in CMOS

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