Electrical and Chemical Studies on Al2O3 Passivation Activation Process

Pawlik, Matthieu; Vilcot, Jean-Pierre; Halbwax, Mathieu; Aureau, Damien; Etchéberry, Arnaud; Slaoui, A.; Schutz-Kuchly, T.; Cabal, R.

doi:10.1016/j.egypro.2014.12.347

Cited by 27 publications

(22 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This may be because only the CZTS surface is exposed to the hydrogen sources like TMA and H 2 O and the process duration is relatively short (only few minutes). Additionally, the process temperature is relatively low, and no postannealing is applied. It makes difficult for hydrogen to penetrate into the bulk.…”

mentioning

confidence: 99%

The Role of Hydrogen from ALD‐Al₂O₃ in Kesterite Cu₂ZnSnS₄ Solar Cells: Grain Surface Passivation

Park

Huang

Yun

et al. 2018

Advanced Energy Materials

View full text Add to dashboard Cite

record 9.5% efficiency pure sulfide CZTS solar cell, [4] but it is still much lower than the S-Q limit and its CuInGaSe 2 (CIGS) counterpart. It has been identified that the main reason for the efficiency limitation is the open-circuit voltage (V oc ) deficit (E g /q −V oc , where q is the elemental charge) as a result of band fluctuation and nonradiative recombination. [5] In addition, unfavorable conduction band alignment, i.e., cliff-like conduction band offset, at the interface of CZTS absorber/ CdS has been reported to lead to high recombination, contributing to the loss of V oc . [6] The majority of electron-hole pairs are generated near the CZTS/CdS interface, [7] so the passivation of the CZTS/ CdS interface is of crucial importance in achieving high-performance CZTS solar cells. In CIGS solar cells, Al 2 O 3 was employed for better surface passivation. [8] In these papers, both field effect passivation by fixed negative charge and chemical passivation play a role in passivating the CIGS surface, and decrease surface recombination velocity. The thickness of Al 2 O 3 used in these studies is few tens of nanometers which are not suitable for the heterojunction passivation as such a thick layer would impede carrier flow at the junction area.We employed an ultrathin atomic layer deposited (ALD)-Al 2 O 3 layer, which is believed to effectively reduce interfacial recombination by reacting with the surface defects. [8a] It is known that, in ALD process, the precursor molecule and the reactant which are trimethylaluminum (TMA, Al(CH 4 ) 3 ) and H 2 O respectively, [9,10] are the hydrogen sources needed for chemical passivation. The passivation mechanism of ALD-Al 2 O 3 in the silicon solar cells can be divided into two categories: i) field effect passivation induced by negative fixed charges [11] and ii) chemical passivation by hydrogen. [12] For field effect passivation, it has been reported that a critical thickness is required to ensure this field effect. [13] Based on the benefits of ALD-Al 2 O 3 , the kesterite group at IBM has recently reported the passivation of CZTSSe/CdS interface by a thin ALD-Al 2 O 3 layer (less than 1 nm) showing enhanced performance due to surface passivation effects. [14] However, the detailed passivation route is unknown. The effect of ultrathin (less than 1 nm) Al 2 O 3 on interface passivation is unclear as negative fixed charges may not be involved in the passivation effect.

show abstract

mentioning

confidence: 99%

The Role of Hydrogen from ALD‐Al₂O₃ in Kesterite Cu₂ZnSnS₄ Solar Cells: Grain Surface Passivation

Park

Huang

Yun

et al. 2018

Advanced Energy Materials

View full text Add to dashboard Cite

show abstract

“…Our previous studies [ 31 ] revealed that the amount of negative oxide charge in the N 2 treated samples depends also on the Al 2 O 3 content, and the layers with a lower Al 2 O 3 content exhibit a lower negative Q ox or even a positive one for the smallest alumina amount in the stack. In this context, it should be noted that the Al 2 O 3 layers commonly demonstrate a negative oxide charge [ 34 , 35 ] unlike the HfO 2 ones whose Q ox is predominantly positive. The short annealing in N 2 [ 35 ] is found to increase the negative Q ox value which is related to reduction of the density of positively charged Al interstitials, whereas the density of negative O interstitials remains unchanged.…”

Section: Resultsmentioning

confidence: 99%

Radiation Tolerance and Charge Trapping Enhancement of ALD HfO2/Al2O3 Nanolaminated Dielectrics

et al. 2021

View full text Add to dashboard Cite

High-k dielectric stacks are regarded as a promising information storage media in the Charge Trapping Non-Volatile Memories, which are the most viable alternative to the standard floating gate memory technology. The implementation of high-k materials in real devices requires (among the other investigations) estimation of their radiation hardness. Here we report the effect of gamma radiation (60Co source, doses of 10 and 10 kGy) on dielectric properties, memory windows, leakage currents and retention characteristics of nanolaminated HfO2/Al2O3 stacks obtained by atomic layer deposition and its relationship with post-deposition annealing in oxygen and nitrogen ambient. The results reveal that depending on the dose, either increase or reduction of all kinds of electrically active defects (i.e., initial oxide charge, fast and slow interface states) can be observed. Radiation generates oxide charges with a different sign in O2 and N2 annealed stacks. The results clearly demonstrate a substantial increase in memory windows of the as-grown and oxygen treated stacks resulting from enhancement of the electron trapping. The leakage currents and the retention times of O2 annealed stacks are not deteriorated by irradiation, hence these stacks have high radiation tolerance.

show abstract

“…Compared to bulk solar cells, nanowire or microwire solar cells typically have a very high surface area and, consequently, a high concentration of surface defects that act as leakage current paths 37,38 . However, the deposited Al 2 O 3 layer provides a high density of negative charges with a very low-density of interface defects 39–41 . Thus, the surface defects and dangling bonds can be effectively passivated.…”

Section: Resultsmentioning

confidence: 99%

Stretchable and colorless freestanding microwire arrays for transparent solar cells with flexibility

et al. 2019

View full text Add to dashboard Cite

Transparent solar cells (TSCs) are emerging devices that combine the advantages of visible transparency and light-to-electricity conversion. Currently, existing TSCs are based predominantly on organics, dyes, and perovskites; however, the rigidity and color-tinted transparent nature of those devices strongly limit the utility of the resulting TSCs for real-world applications. Here, we demonstrate a flexible, color-neutral, and high-efficiency TSC based on a freestanding form of n-silicon microwires (SiMWs). Flat-tip SiMWs with controllable spacing are fabricated via deep-reactive ion etching and embedded in a freestanding transparent polymer matrix. The light transmittance can be tuned from ~10 to 55% by adjusting the spacing between the microwires. For TSCs, a heterojunction is formed with a p-type polymer in the top portion of the n-type flat-tip SiMWs. Ohmic contact with an indium-doped ZnO film occurs at the bottom, and the side surface has an Al2O3 passivation layer. Furthermore, slanted-tip SiMWs are developed by a novel solvent-assisted wet etching method to manipulate light absorption. Finite-difference time-domain simulation revealed that the reflected light from slanted-tip SiMWs helps light-matter interactions in adjacent microwires. The TSC based on the slanted-tip SiMWs demonstrates 8% efficiency at a visible transparency of 10% with flexibility. This efficiency is the highest among Si-based TSCs and comparable with that of state-of-the-art neutral-color TSCs based on organic–inorganic hybrid perovskite and organics. Moreover, unlike others, the stretchable and transparent platform in this study is promising for future TSCs.

show abstract

Electrical and Chemical Studies on Al2O3 Passivation Activation Process

Cited by 27 publications

References 10 publications

The Role of Hydrogen from ALD‐Al₂O₃ in Kesterite Cu₂ZnSnS₄ Solar Cells: Grain Surface Passivation

The Role of Hydrogen from ALD‐Al₂O₃ in Kesterite Cu₂ZnSnS₄ Solar Cells: Grain Surface Passivation

Radiation Tolerance and Charge Trapping Enhancement of ALD HfO2/Al2O3 Nanolaminated Dielectrics

Stretchable and colorless freestanding microwire arrays for transparent solar cells with flexibility

Contact Info

Product

Resources

About

Electrical and Chemical Studies on Al2O3 Passivation Activation Process

Cited by 27 publications

References 10 publications

The Role of Hydrogen from ALD‐Al2O3 in Kesterite Cu2ZnSnS4 Solar Cells: Grain Surface Passivation

The Role of Hydrogen from ALD‐Al2O3 in Kesterite Cu2ZnSnS4 Solar Cells: Grain Surface Passivation

Radiation Tolerance and Charge Trapping Enhancement of ALD HfO2/Al2O3 Nanolaminated Dielectrics

Stretchable and colorless freestanding microwire arrays for transparent solar cells with flexibility

Contact Info

Product

Resources

About

The Role of Hydrogen from ALD‐Al₂O₃ in Kesterite Cu₂ZnSnS₄ Solar Cells: Grain Surface Passivation

The Role of Hydrogen from ALD‐Al₂O₃ in Kesterite Cu₂ZnSnS₄ Solar Cells: Grain Surface Passivation