Reactive ion etching of dielectrics and silicon for photovoltaic applications

Deenapanray, Prakash; Athukorala, Chintana; Macdonald, Daniel; Jellett, Wendy; Franklin, Evan; Everett, Vernie; Weber, Klaus; Blakers, Andrew

doi:10.1002/pip.684

Cited by 10 publications

(4 citation statements)

References 31 publications

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“…On the other hand, the nanostructure is patterned by LIL and it is transferred to silicon nitride by reactive ion etching (RIE). LIL is suitable for photovoltaics as discussed in the introduction, whereas RIE is widely used in photovoltaics and microelectronics3132333435.…”

Section: Experimental Methodsmentioning

confidence: 99%

Nano-cones for broadband light coupling to high index substrates

Buencuerpo

Torne

Álvaro

et al. 2016

Sci Rep

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The moth-eye structure has been proposed several times as an antireflective coating to replace the standard optical thin films. Here, we experimentally demonstrate the feasibility of a dielectric moth-eye structure as an antireflective coating for high-index substrates, like GaAs. The fabricated photonic crystal has Si3N4 cones in a square lattice, sitting on top of a TiO2 index matching layer. This structure attains 1.4% of reflectance power losses in the operation spectral range of GaAs solar cells (440–870 nm), a 12.5% relative reduction of reflection power losses in comparison with a standard bilayer. The work presented here considers a fabrication process based on laser interference lithography and dry etching, which are compatible with solar cell devices. The experimental results are consistent with scattering matrix simulations of the fabricated structures. In a broader spectral range (400–1800 nm), the simulation estimates that the nanostructure also significantly outperforms the standard bilayer coating (3.1% vs. 4.5% reflection losses), a result of interest for multijunction tandem solar cells.

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Section: Experimental Methodsmentioning

confidence: 99%

Nano-cones for broadband light coupling to high index substrates

Buencuerpo

Torne

Álvaro

et al. 2016

Sci Rep

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“…The data points for CHF 3 /O 2 reactive ion etching are taken from our previous study and are included here for comparison only. 19 In general, the increase in etch rate with rf power is due to the increase in the physical component of etching ͑i.e., sputtering͒, as shown by the increase in dc bias with rf power in Fig. 3͑b͒.…”

Section: B Rf-power Dependence Of Etch Ratesmentioning

confidence: 99%

“…Since O 2 effectively minimizes the thickness of the polymer layer as discussed previously, we have explained the monotonic increase in etch rates in CHF 3 /O 2 by increasing physical sputtering. 19 In contrast to etching in CHF 3 /O 2 , there is a threshold rf power for etching to take place in CHF 3 / Ar. This result is similar to RIE in CF 4 /H 2 observed in Ref.…”

Section: B Rf-power Dependence Of Etch Ratesmentioning

confidence: 99%

Investigation of reactive ion etching of dielectrics and Si in CHF3∕O2 or CHF3∕Ar for photovoltaic applications

Gatzert¹,

Blakers²,

Deenapanray³

et al. 2006

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Using a combination of etch rate, photoconductance, and deep level transient spectroscopy ͑DLTS͒ measurements, the authors have investigated the use of reactive ion etching ͑RIE͒ of dielectrics and Si in CHF 3 /O 2 and CHF 3 / Ar plasmas for photovoltaic applications. The radio frequency power ͑rf-power͒ and gas flow rate dependencies have shown that the addition of either O 2 or Ar to CHF 3 can be used effectively to change the etch selectivity between SiO 2 and Si 3 N 4. The effective carrier lifetime of samples degraded upon exposure to a CHF 3-based plasma, reflecting the introduction of recombination centers in the near-surface region. The extent of minority carrier lifetime degradation was similar in both types of plasmas, suggesting that the same defects were responsible for the increased recombination. However, the rf-power dependence of lifetime degradation in n-and p-type Si was different. Moreover, the lifetime degradation did not exhibit a linear rf-power dependence, suggesting that primary defects were not the dominant recombination centers responsible for the decrease in lifetime. Indeed, DLTS measurements have shown that secondary defects were formed in samples exposed to the plasma after annealing at 400°C, the temperature at which a SiN:H layer is deposited on samples to passivate their surfaces. The minority carrier lifetime degradation in RIE processed samples could be partially avoided using post-RIE chemical treatments.

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“…However, RIE generates defects in the near-surface region of the semiconductor [13][14][15], thus degrading the electrical performance of solar cells and other devices [16][17][18][19]. Deenapanray characterised the reaction mechanism of RIE etching of silicon, SiO 2 and SiN x against varied etch parameters [20,21], and also studied lifetime degradation and defect characterisation in RIE-processed silicon samples [22]. SLIVER technology developed by Blakers and Weber enables the production of 20% efficient cells by incorporating the benefits of RIE [23,24].…”

Section: Introductionmentioning

confidence: 99%

RIE‐induced carrier lifetime degradation

Zin

Blakers

Weber

2010

Progress in Photovoltaics

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Reactive Ion Etching (RIE) is used in the fabrication of some types of solar cells to achieve a highly directional etch. However, cells fabricated using RIE have lower than expected efficiency, possibly caused by increased carrier recombination. Characterisation of the carrier lifetime in solar cells was conducted using the quasi steady state photoconductance (QSSPC) measurement technique. Substantial effective lifetime degradation was observed for silicon samples processed by RIE. Lifetime degradation for samples where RIE etches into silicon is found to be permanent, while for samples where RIE etches only on dielectric layers of SiO 2 grown on the wafer, the lifetime degradation is found to be reversible. The reversible degradation in RIE-processed samples is associated with radiation damage. By reducing the proportion of a wafer exposed to RIE, the degradation of the effective lifetime of RIE-etched silicon samples can be minimised, and the performance of silicon solar cells can be improved significantly.

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Reactive ion etching of dielectrics and silicon for photovoltaic applications

Cited by 10 publications

References 31 publications

Nano-cones for broadband light coupling to high index substrates

Nano-cones for broadband light coupling to high index substrates

Investigation of reactive ion etching of dielectrics and Si in CHF3∕O2 or CHF3∕Ar for photovoltaic applications

RIE‐induced carrier lifetime degradation

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