Theory of a carbon‐oxygen‐hydrogen recombination center in n‐type Si

Santos, P.; Coutinho, J.; Öberg, Sven; Vaqueiro-Contreras, Michelle; Markevich, V. P.; Halsall, Matthew P.; Peaker, А. R.

doi:10.1002/pssa.201700309

Cited by 7 publications

(5 citation statements)

References 25 publications

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“…In the literature, while hydrogenation has been proven to be effective in improving the performance of solar cells, ,− hydrogen has been shown to cause recombination in multiple ways, such as formation of structural defects or platelets, , deactivation of phosphorus dopants, formation of powerful recombination centers composed of carbon, oxygen, and hydrogen, , and creation of vacancy-hydrogen complexes . It was also suggested that hydrogen itself could cause recombination, potentially resulting in a reduction in the carrier lifetime, which might also be a possible explanation for the impact of excess hydrogen observed herein.…”

Section: Resultsmentioning

confidence: 67%

Optimum Hydrogen Injection in Phosphorus-Doped Polysilicon Passivating Contacts

Kang

Sio

Stückelberger

et al. 2021

ACS Appl. Mater. Interfaces

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It has previously been shown that ex situ phosphorus-doped polycrystalline silicon on silicon oxide (poly-Si/SiO x ) passivating contacts can suffer a pronounced surface passivation degradation when subjected to a firing treatment at 800 °C or above. The degradation behavior depends strongly on the processing conditions, such as the dielectric coating layers and the firing temperature. The current work further studies the firing stability of poly-Si contacts and proposes a mechanism for the observed behavior based on the role of hydrogen. Secondary ion mass spectrometry is applied to measure the hydrogen concentration in the poly-Si/SiO x structures after firing at different temperatures and after removing hydrogen by an anneal in nitrogen. While it is known that a certain amount of hydrogen around the interfacial SiO x can be beneficial for passivation, surprisingly, we found that the excess amount of hydrogen can deteriorate the poly-Si passivation and increase the recombination current density parameter J 0. The presence of excess hydrogen is evident in selected poly-Si samples fired with silicon nitride (SiN x ), where the injection of additional hydrogen to the SiO x interlayer leads to further degradation in the J 0, while removing hydrogen fully recovers the surface passivation. In addition, the proposed model explains the dependence of firing stability on the crystallite properties and the doping profile, which determine the effective diffusivity of hydrogen upon firing and hence the amount of hydrogen around the interfacial SiO x after firing.

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Section: Resultsmentioning

confidence: 67%

Optimum Hydrogen Injection in Phosphorus-Doped Polysilicon Passivating Contacts

Kang

Sio

Stückelberger

et al. 2021

ACS Appl. Mater. Interfaces

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show abstract

“…DLTS and MCTS spectra recorded on a sample from n-type Cz silicon containing oxygen-related thermal double donors (E 4 trap) with a high concentration and C-O-H defects (E 1 /H 1 and E 2 /H 2 traps). 38,39 The spectra were recorded with a rate window corresponding to e = 50 s 38,39 It appears that there is a small population of majority carriers in the depletion region during the MCTS experiment as can be seen from the majority carrier peak in the low temperature region. This peak is due to the second donor level of oxygen-related thermal double donors having a large electron capture cross section.…”

Section: Minority Carrier Processes and Carrier Capture Measurementsmentioning

confidence: 99%

Tutorial: Junction spectroscopy techniques and deep-level defects in semiconductors

Peaker

Markevich

Coutinho

2018

Journal of Applied Physics

103

107

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The term junction spectroscopy embraces a wide range of techniques used to explore the properties of semiconductor materials and semiconductor devices. In this tutorial review we describe the most widely used junction spectroscopy approaches for characterizing deep-level defects in semiconductors and present some of the early work on which the principles of today's methodology are based. We outline ab-initio calculations of defect properties and give examples of how density functional theory in conjunction with formation energy and marker methods can be used to guide the interpretation of experimental results. We review recombination, generation and trapping of charge carriers associated with defects. We consider thermally driven emission and capture and describe the techniques of Deep Level Transient Spectroscopy (DLTS), high resolution Laplace DLTS, admittance spectroscopy and scanning DLTS. For the study of minority carrier related processes and wide gap materials we consider Minority Carrier Transient Spectroscopy (MCTS), Optical DLTS (ODLTS and DLOS) together with some of their many variants. Capacitance, current and conductance measurements enable carrier exchange processes associated with the defects to be detected. We explain how these methods are used in order to understand the behaviour of point defects, the determination of charge states and negative-U (Hubbard correlation energy) behaviour. We provide, or reference, examples from a wide range of materials including Si, SiGe, GaAs, GaP, GaN, InGaN, InAlN and ZnO.

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“…11 The possible structures of the C-O-H complex with electronic properties close to those for the H 1 and H 2 traps have been found from the first principles calculations. 11,17 Here, we present results of a study of the electronic properties and thermal stability of the E 1 , E 2, and E 4 electron traps and some results on the relation of these traps to the most abundant oxygen, carbon, and hydrogen impurities. It should be noted, however, that the E 1 -E 4 traps do not appear to be the significant recombination centers for holes in n-type Si crystals because of the closeness of their energy levels to the conduction band edge.…”

Section: A Effect Of Hydrogenation Treatments On Minority Carrier Lifetime In N-type Cz-simentioning

confidence: 99%

Lifetime degradation of n-type Czochralski silicon after hydrogenation

Vaqueiro-Contreras

Markevich

Mullins

et al. 2018

Journal of Applied Physics

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Hydrogen plays an important role in the passivation of interface states in silicon-based metal-oxide semiconductor technologies and passivation of surface and interface states in solar silicon. We have shown recently [Vaqueiro-Contreras et al., Phys. Status Solidi RRL 11, 1700133 (2017)] that hydrogenation of n-type silicon slices containing relatively large concentrations of carbon and oxygen impurity atoms {[C s ] ! 1 Â 10 16 cm À3 and [O i ] ! 10 17 cm À3 } can produce a family of C-O-H defects, which act as powerful recombination centres reducing the minority carrier lifetime. In this work, evidence of the silicon's lifetime deterioration after hydrogen injection from SiN x coating, which is widely used in solar cell manufacturing, has been obtained from microwave photoconductance decay measurements. We have characterised the hydrogenation induced deep level defects in n-type Czochralski-grown Si samples through a series of deep level transient spectroscopy (DLTS), minority carrier transient spectroscopy (MCTS), and high-resolution Laplace DLTS/MCTS measurements. It has been found that along with the hydrogen-related hole traps, H 1 and H 2 , in the lower half of the gap reported by us previously, hydrogenation gives rise to two electron traps, E 1 and E 2 , in the upper half of the gap. The activation energies for electron emission from the E 1 and E 2 trap levels have been determined as 0.12, and 0.14 eV, respectively. We argue that the E 1 /H 1 and E 2 /H 2 pairs of electron/hole traps are related to two energy levels of two complexes, each incorporating carbon, oxygen, and hydrogen atoms. Our results show that the detrimental effect of the C-O-H defects on the minority carrier lifetime in n-type Si:O þ C materials can be very significant, and the carbon concentration in Czochralski-grown silicon is a key parameter in the formation of the recombination centers. V

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Theory of a carbon‐oxygen‐hydrogen recombination center in n‐type Si

Cited by 7 publications

References 25 publications

Optimum Hydrogen Injection in Phosphorus-Doped Polysilicon Passivating Contacts

Optimum Hydrogen Injection in Phosphorus-Doped Polysilicon Passivating Contacts

Tutorial: Junction spectroscopy techniques and deep-level defects in semiconductors

Lifetime degradation of n-type Czochralski silicon after hydrogenation

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