Electrical response of electron selective atomic layer deposited TiO<sub>2−x</sub>heterocontacts on crystalline silicon substrates

Ahiboz, Doğuşcan; Nasser, Hisham; Aygun, E.; Bek, Alpan; Turan, Raşit

doi:10.1088/1361-6641/aab535

Cited by 8 publications

(12 citation statements)

References 36 publications

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“…Though these designs have reached an advanced stage in the development of efficient c‐Si solar cells, there still exist several challenges such as thermal instability, strong parasitic light absorption by the utilized thin films, especially a‐Si:H due to its rather small band gap, and the used inevitable complicated deposition processes by PECVD followed by photolithography and/or laser steps. Recently, there has been a considerable attention to use alternative dopant‐free CSCs for c‐Si solar cells due to their unique work function values, considerably large band gap, simpler contact formation, and ease of production by simpler techniques 4–12 . These dopant‐free CSCs have shown to remove fundamental limitations associated with doped Si layers such as Auger recombination, parasitic light absorption, and free carrier absorption 13–15 .…”

Section: Introductionmentioning

confidence: 99%

On the application of hole‐selective MoO_x as full‐area rear contact for industrial scale p‐type c‐Si solar cells

Nasser

Borra

et al. 2020

Progress in Photovoltaics

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We present the feasibility of integrating substoichiometric molybdenum oxide (MoOx) as hole‐selective rear contact into the production sequence of industrial scale p‐type crystalline silicon (c‐Si) solar cells. Thin films of MoOx are deposited directly on p‐type c‐Si by thermal evaporation at room temperature. It is found that Ag/MoOx/p‐type c‐Si rear contact structure exhibits low contact resistivity and modest surface recombination current density. The attained peak efficiency (η) of the fabricated solar cells is 17.65% with Voc of 626 mV, Jsc of 36.8 mA/cm2, and fill factor (FF) of 76.63%. Next, a complete loss analysis of a MoOx/p‐type Si heterojunction solar cell is carried out for the first time by using Quokka simulation software that employs characteristics of different layers which constitute the fabricated solar cell. Based on this loss analysis, the dominant loss mechanisms are defined and a roadmap to attain the desired highest possible efficiency from industrial scale p‐type c‐Si solar cells with full‐area MoOx hole‐collecting rear contact is explored.

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Section: Introductionmentioning

confidence: 99%

On the application of hole‐selective MoO_x as full‐area rear contact for industrial scale p‐type c‐Si solar cells

Nasser

Borra

et al. 2020

Progress in Photovoltaics

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“…Table 1 tabulates the relevant electrical data for n-cSi, a-Si:H, and TiO x layers used in the simulation that have been extracted from the appropriate literature. 63,66,[68][69][70][71] The parameters for MoO x and defects states of a-Si:H have been extracted from our earlier reported works. 63 For physical device modelling of solar cells, it is pertinent to include relevant physical models in the simulation code that are needed to compute the essential output parameters of the studied devices.…”

Section: Tcad Modelling Of the Proposed Devicementioning

confidence: 99%

“…The electrodes of anode and cathode have been realized with silver (Ag) and aluminium (Al) contacts at the front and rear of the device, respectively. Table 1 tabulates the relevant electrical data for n‐cSi, a‐Si:H, and TiO x layers used in the simulation that have been extracted from the appropriate literature 63,66,68‐71 . The parameters for MoO x and defects states of a‐Si:H have been extracted from our earlier reported works 63 …”

Section: Tcad Modelling Of the Proposed Devicementioning

confidence: 99%

Numerical analysis of dopant‐free asymmetric silicon heterostructure solar cell with SiO ₂ as passivation layer

et al. 2020

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Conventional silicon heterojunction solar cells employ defects-prone a-Si:H layers for junction formation and passivation purposes. Substituting these layers with hole-selective MoO x and electron-selective TiO x can reduce parasitic absorption and energy band offsets issues associated with doped silicon films. In this work, dopant-free asymmetric heterostructure Si solar cells are studied with and without SiO 2 passivation layer, and their performance has been compared. The inclusion of ultrathin SiO 2 insulator as a passivation layer promotes significant band bending that induces interface inversion of crystalline silicon as well as maintains the electric field required to tunnel charge carriers. The energy band diagram studies and variation of oxide thickness show that the IV characteristics of the solar cell critically depend on the insulator thickness; as the carriers tunnelling through the insulator becomes negligible at larger thicknesses. The simulated structure with MoO x as front holeselective contact and without any passivation exhibited conversion efficiency of 15.73%, which improved to 18.69% by incorporating passivated a-Si:H. However, by employing rear SiO 2 /TiO x stack with the front SiO 2 /MoO x , the device performance enhanced to open-circuit voltage of 785 mV, short-circuit current density of 41 mA/cm 2 , fill factor of 77%, and simulated conversion efficiency of 24.83%, which is~10% enhancement in the performance as compared to reference device employing traditional a-Si:H with dopant-free films. Novelty Statement For the first time, a dopant-free asymmetric silicon heterostructure solar cell (DASH) employing silicon oxide (SiO 2) as a passivation layer has been physically modelled using Silvaco TCAD. The dopant-free MoO x and TiO x as holeand electron-selective contacts have been incorporated. An ultrathin SiO 2 promotes band bending that induces interface inversion of absorber as well as facilitating carrier tunnelling. An efficiency of 24.83% has been numerically attained which is the best performance among DASH structures designed with oxide passivation. The 2-D cross-section view of the proposed device employing dopant-free layers and oxide passivated film is illustrated in Figure 1 for which we have applied memory intensive numerical method based on the computation of Poisson, charge transport and continuity equations in the Silvaco ATLAS

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“…The electrical properties of TiO 2 thin films grown by atomic layer deposition (ALD) on crystalline silicon substrates were studied recently [17]. It was found that a heterojunction was formed between the deposited TiO 2 and silicon substrate demonstrating nonohmic and asymmetric current-voltage characteristics.…”

Section: Introductionmentioning

confidence: 99%

“…It was found that a heterojunction was formed between the deposited TiO 2 and silicon substrate demonstrating nonohmic and asymmetric current-voltage characteristics. Usually, TiO 2 is treated as an n-type semiconductor with a wide bandgap reaching 3.4 eV, 3.2 eV, 3.02 eV and 2.96 eV for amorphous, anatase, rutile and brookite phases, respectively [17,18]. Therefore, nondoped, high quality TiO 2 has a high resistivity and may serve as an insulator for capacitors [19,20].…”

Section: Introductionmentioning

confidence: 99%

Low Resistance TiO2/p-Si Heterojunction for Tandem Solar Cells

et al. 2020

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Niobium-doped titanium dioxide (Ti1−xNbxO2) films were grown on p-type Si substrates at low temperature (170 °C) using an atomic layer deposition technique. The as-deposited films were amorphous and showed low electrical conductivity. The films became electrically well-conducting and crystallized into the an anatase structure upon reductive post-deposition annealing at 600 °C in an H2 atmosphere for 30 min. It was shown that the Ti0.72Nb0.28O2/p+-Si heterojunction fabricated on low resistivity silicon (10−3 Ω cm) had linear current–voltage characteristic with a specific contact resistivity as low as 23 mΩ·cm2. As the resistance dependence on temperature revealed, the current across the Ti0.72Nb0.28O2/p+-Si heterojunction was mainly determined by the band-to-band charge carrier tunneling through the junction.

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Electrical response of electron selective atomic layer deposited TiO_2−xheterocontacts on crystalline silicon substrates

Cited by 8 publications

References 36 publications

On the application of hole‐selective MoO_x as full‐area rear contact for industrial scale p‐type c‐Si solar cells

On the application of hole‐selective MoO_x as full‐area rear contact for industrial scale p‐type c‐Si solar cells

Numerical analysis of dopant‐free asymmetric silicon heterostructure solar cell with SiO ₂ as passivation layer

Low Resistance TiO2/p-Si Heterojunction for Tandem Solar Cells

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Electrical response of electron selective atomic layer deposited TiO2−xheterocontacts on crystalline silicon substrates

Cited by 8 publications

References 36 publications

On the application of hole‐selective MoOx as full‐area rear contact for industrial scale p‐type c‐Si solar cells

On the application of hole‐selective MoOx as full‐area rear contact for industrial scale p‐type c‐Si solar cells

Numerical analysis of dopant‐free asymmetric silicon heterostructure solar cell with SiO 2 as passivation layer

Low Resistance TiO2/p-Si Heterojunction for Tandem Solar Cells

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Resources

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Electrical response of electron selective atomic layer deposited TiO_2−xheterocontacts on crystalline silicon substrates

On the application of hole‐selective MoO_x as full‐area rear contact for industrial scale p‐type c‐Si solar cells

On the application of hole‐selective MoO_x as full‐area rear contact for industrial scale p‐type c‐Si solar cells

Numerical analysis of dopant‐free asymmetric silicon heterostructure solar cell with SiO ₂ as passivation layer