Proof-of-concept framework to separate recombination processes in thin silicon wafers using transient free-carrier absorption spectroscopy

Siah, Sin Cheng; Winkler, M.; Powell, Douglas M.; Johnston, Steven W.; Kanevce, Ana; Levi, Dean H.; Buonassisi, Tonio

doi:10.1063/1.4914160

Cited by 4 publications

(2 citation statements)

References 35 publications

(45 reference statements)

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“…1 shows the symmetrical a-Si:H(i)/c-Si/a-Si:H(i) structure. The MCLT was measured using a Sinton Consulting (WTC-120) quasi-steady-state photoconductance (QSSPC) lifetime tester in transient mode [10,11] . The morphology and the feature of the a-Si:H(i)/c-Si interface was examined using transmission electron microscopy (TEM) technology.…”

Section: Methodsmentioning

confidence: 99%

Pyramid size control and morphology treatment for high-efficiency silicon heterojunction solar cells

Tian

Han

Zhao³

et al. 2019

J. Semicond.

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This paper investigates the formation process of surface pyramid and etching characteristics during the texturing process of mono-crystalline silicon wafers. It is found that there is an etch rate transition point in alkaline anisotropic etching when {100} plane-dominated etch turns to {111} plane-dominated etch, and the pyramid size has a strong linear correlation with the etch amount at the transition point. Several techniques were developed to control the pyramid size by monitoring and adjusting the etching amount. A wide range of average pyramid sizes were successfully achieved, from 0.5 to 12 μm. The experiments of the pyramid size on the light reflectance, the minority carrier lifetime (MCLT), and the performance of silicon heterojunction (SHJ) solar cells were carried out and analyzed. A desirable range of pyramid sizes was empirically determined by our investigation. In order to reduce the density states on the texturing surface, the wet-chemical smoothing treatment was also investigated. The smoothing treatment improves the passivation quality and the performance of the solar cells. Through pyramid size control and morphology treatment, together with the amorphous silicon (a-Si:H) deposition improvement, and electrode optimization, high performance of SHJ solar cells has been achieved, up to conversion efficiency 23.6%.

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Section: Methodsmentioning

confidence: 99%

Pyramid size control and morphology treatment for high-efficiency silicon heterojunction solar cells

Tian

Han

Zhao³

et al. 2019

J. Semicond.

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“…Trapping at deep impurity states and defect scattering has received little attention from the ab initio community despite being a crucial issue in CSC active layer materials. 147,192 Bridging ab initio calculations of mobilities and conductivities to device-scale drift-diffusion or Monte Carlo simulations also appears to be an important challenge to comprehensively model solar cells. The main goal in this area is to obtain current-voltage curves for devices under operating conditions.…”

Section: Outlook and Future Challengesmentioning

confidence: 99%

Computer calculations across time and length scales in photovoltaic solar cells

Bernardi

Grossman

2016

Energy Environ. Sci.

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Photovoltaic (PV) solar cells convert solar energy to electricity through a cascade of microscopic processes spanning over 10 order of magnitudes of time and length. PV conversion involves a complex interplay of photons, charge carriers, and excited states. Processes following light absorption include generation of charge carriers or excitons, exciton dissociation over nanometer lengths and subpicosecond times, and carrier transport over ns-ms times and nm-mm lengths. Computer calculations have become an indispensable tool to understand and engineer solar cells across length and time scales. In this article, we examine the microscopic processes underlying PV conversion and review state-of-the-art computational methods to study PV solar cells. Recent developments and future research challenges are outlined.

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Intrinsic shape of free carrier absorption spectra in 4H-SiC

Grivickas

Redeckas

Gulbinas

et al. 2019

Journal of Applied Physics

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Free carrier absorption spectra are measured along the different polarization directions with respect to the c-axis of 4H-SiC using ultrafast differential transmission spectroscopy. Probing of excited carrier spectra in an undoped material reveals intrinsic resonances within the conduction band. Widths of the detected resonance peaks are shown to be wider than their theoretical estimates and more comparable to the ones observed in a low doped material. Relative strength of the peaks, on the other hand, is shown to be nearly excitation independent in contrast to the doping induced absorption weakening for the same transitions in n-type samples. Free carrier cross sections are extracted from the excitation dependency of the detected spectra and linked to the individual electron and hole contributions in the near infrared range.

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Proof-of-concept framework to separate recombination processes in thin silicon wafers using transient free-carrier absorption spectroscopy

Cited by 4 publications

References 35 publications

Pyramid size control and morphology treatment for high-efficiency silicon heterojunction solar cells

Pyramid size control and morphology treatment for high-efficiency silicon heterojunction solar cells

Computer calculations across time and length scales in photovoltaic solar cells

Intrinsic shape of free carrier absorption spectra in 4H-SiC

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