Effective Minority Carrier Lifetime Research Articles

Influence of Substrate Properties on the Defectivity and Minority Carrier Lifetime in 4H-SiC Homoepitaxial Layers

Two fully loaded epitaxial growth runs with 16 wafers in total were conducted in the AIXTRON G5 WW reactor in order to keep epigrowth conditions constant. The wafers were selected with a large spread of specific resistivity and dislocation densities. The resulting epilayers showed very good intra-wafer homogeneities as well as excellent wafer-to-wafer and run-to-run reproducibility with regard to epilayer thickness and doping concentration, point defect concentrations of Z1/2 and EH6/7 and the resulting Shockley-Read-Hall carrier lifetime. We found that the dislocation densities of the underlying substrates are influencing the stacking fault densities of the epilayers, which then vary between 0.1 and 10 cm-2. A substrate effect on the effective minority carrier lifetime was found.

Design Principles for Fabrication of InP-Based Radial Junction Nanowire Solar Cells Using an Electron Selective Contact

Nanowire solar cells hold several advantages over planar solar cells, such as reduced reflection, facile strain relaxation, extreme light trapping, increased defect tolerance, etc. However, because of their large surface-to-volume ratio, nanowires tend to have very low effective minority carrier lifetime. To overcome this issue, a radial junction solar cell was proposed. However, in experimental realization, the efficiency of a radial junction solar cell remains significantly lower than its axial counterpart. This is mainly because of the inability to simultaneously control the doping in both the core and the shell while maintaining low defect density at the interface. To overcome the above-mentioned issues, we propose and simulate a core–shell heterojunction solar cell using p-InP as a core material and ITO/ZnO as a shell material. Using finite-difference time-domain simulations, we show that use of an oxide coating over InP core can significantly increase the absorption in InP nanowire arrays, and for an optimized thickness of oxide layer, InP consumption can be reduced by as much as four folds without sacrificing the ideal short circuit current. In addition, our device simulation results show that even for a core minority carrier lifetime of 50 ps, an efficiency of 23% can be obtained if both core and shell can be heavily doped while maintaining an interface recombination velocity of less than 104 cm/s. Finally, we discuss how the proposed device structure can reduce the fabrication complexities related to epitaxial homojunction/heterojunction core–shell solar cell structure while achieving a high efficiency under optimized conditions.

Wet chemical surface smoothing method for improving surface passivation on monocrystalline silicon

We have adopted an appropriate HNO3-HF-H2O mixed solution to smooth the surface of the silicon wafer. The solution evidently reduces the surface roughness of double-side chemical polished c-Si, and the interface state density (Dit) decreases from 1011 cm−2 eV−1 to 1010 cm−2 eV−1 at the mid-gap energy level. Therefore the effective minority carrier lifetime (τeff) of silicon wafer increases from 259 us to 273 us. Replace it with textured c-Si, the weighted reflectance of silicon increases to 15.9% from 11.97%; and τeff is also up to the highest value of 437 us at 1000 s from 221 us of as-prepared textured silicon.

An industrially viable TOPCon structure with both ultra-thin SiOx and n+-poly-Si processed by PECVD for p-type c-Si solar cells

We report an industrial compatible tunnel oxide passivated contact (TOPCon) structure on solar-grade p-type c-Si wafer as the rear emitter for high-efficiency solar cells, where the ultrathin silicon oxide (SiOx) is made by plasma-assisted oxidation and the P-doped n-type poly-Si (n+-poly-Si) contact layer by plasma-enhanced chemical vapor deposition (PECVD) of hydrogenated amorphous silicon (a-Si:H) with in-situ doping with PH3 and following the high-temperature annealing. The fabrication processes of SiOx and n+-poly-Si layers are systematically optimized. It is found that the optimized annealing temperature for the crystallization and dopant activation is in the range of 850 °C and 880 °C, which is higher than the similar structure with chemically oxidized SiOx (820 °C). In addition, the samples made with higher PH3/SiH4 doping ratio during the a-Si:H deposition need a lower annealing temperature to reach the similar dopant distribution within the samples made with lower doping ratio but annealed at higher temperature, it means that the optimized annealing temperature decreases with the increase of the PH3/SiH4 doping ratio during the deposition of a-Si:H precursor. The optimized process with post-hydrogenation yields excellent surface passivation on the p-type Si substrate with the implied open-circuit voltage (iVoc) of ∼742 mV, the single-side saturated recombination current density (J0) of ∼3.0 fA/cm2, the contact resistivity (ρc) of ∼2–4 mΩ cm2, and the effective minority carrier lifetime (τeff) of ∼1050 μs (Δn = 1 × 1015 cm-3). With these passivation parameters, a simulation study demonstrates the advantage of rear emitter over the conventional front emitter TOPCon solar cell with ∼22.8% achievable efficiency on solar-grade p-type wafers with current industrial constraints, and ∼24.9% on high quality p-type c-Si wafers with the optimized conditions in R&D laboratories. Our study suggests that the p-type c-Si solar cell with a rear n+-poly-Si TOPCon emitter is a viable structure for high-efficiency solar cell production.

Roles of hydrogen atoms in p-type Poly-Si/SiOx passivation layer for crystalline silicon solar cell applications

Cyclic dehydrogenation-rehydrogenation experiments have been performed on p-type poly-Si/SiOx stack to study the roles of hydrogen (H) atoms for crystalline silicon (c-Si) surface passivation. The effective lifetime of minority carriers is enhanced to 1.4 ms by the hydrogenation of hydrogen plasma treatment (HPT) at 300 °C. The dehydrogenation by thermal annealing at 450 °C decreases the lifetime to ∼0.6 ms, which is recovered by a consecutive HPT, underlining the c-Si surface passivation by H atoms diffused into the SiOx/c-Si interface. The lifetime recovery follows a stretched exponential function, indicating the dispersive nature of the p-type poly-Si/SiOx stack.

Time-resolved photoluminescence on double graded Cu(In,Ga)Se2 – Impact of front surface recombination and its temperature dependence

ABSTRACT Time-resolved photoluminescence (TRPL) is applied to determine an effective lifetime of minority charge carriers in semiconductors. Such effective lifetimes include recombination channels in the bulk as well as at the surfaces and interfaces of the device. In the case of Cu(In,Ga)Se2 absorbers used for solar cell applications, trapping of minority carriers has also been reported to impact the effective minority carrier lifetime. Trapping can be indicated by an increased temperature dependence of the experimentally determined photoluminescence decay time when compared to the temperature dependence of Shockley–Read–Hall (SRH) recombination alone and can lead to an overestimation of the minority carrier lifetime. Here, it is shown by technology computer-aided design (TCAD) simulations and by experiment that the intentional double-graded bandgap profile of high efficiency Cu(In,Ga)Se2 absorbers causes a temperature dependence of the PL decay time similar to trapping in case of a recombinative front surface. It is demonstrated that a passivated front surface results in a temperature dependence of the decay time that can be explained without minority carrier trapping and thus enables the assessment of the absorber quality by means of the minority carrier lifetime. Comparison with the absolute PL yield and the quasi-Fermi-level splitting (QFLS) corroborate the conclusion that the measured decay time corresponds to the bulk minority carrier lifetime of 250 ns for the double-graded CIGS absorber under investigation.

Control of solution wettability on fine-textured crystalline silicon surface to obtain high-quality passivation for solar cells

We developed a suitable chemical cleaning procedure for a fine-textured crystalline silicon (c-Si) surface which was prepared by the microparticle-assisted texturing (MPAT) process. This cleaning is a key to obtaining high-quality surface passivation by catalytic chemical vapor deposition (Cat-CVD) of silicon nitride (SiNx)/amorphous silicon (a-Si) stacked layers. In the cleaning, hydrofluoric acid (HF) solutions were used for surface oxide removal. Due to the weak wettability of the solution on the c-Si surface, the oxide layer was not entirely removed, leading to a bad surface passivation. We controlled the wettability of the solutions by adding methanol with different mixing ratios. We named this technique as the methanol-assisted cleaning (MAC) process. As a result, the effective minority carrier lifetime (τeff) increased from a few milliseconds to ∼7.8 ms, corresponding to an extremely low surface recombination velocity (SRV) of ∼0.6 cm/s, when the mixing ratio is ∼50 vol. %. Note that τeff reaches almost a world-record value for textured c-Si passivated by Cat-CVD SiNx/a-Si. Since the HF solution is widely used in industry for cleaning the Si surface, the control of its wettability becomes a promising and fundamental application.

Effect of textured silicon pyramids size and chemical polishing on the performance of carrier-selective contact heterojunction solar cells

Role of textured crystalline silicon pyramids size and chemical polishing (CP) for isotropic etching of pyramid peaks/valleys are investigated from carrier-selective contact silicon heterojunction solar cell performance. With an increase of average pyramids size from 2 to 8 µm, the effective minority carrier lifetimes (τeff) are reduced from ∼126 to ∼65 µs with molybdenum oxide (MoOx) surface passivation layers. After the CP treatment, an increase in the τeff is observed for the same respective textures (from ∼154 to ∼99 µs) due to reduction of charge carrier recombination. The solar cell structure of Ag/ITO/MoOx/n-Si/LiFx/Al is fabricated at room temperature. With small pyramids (∼2 µm), the cell has shown the better power conversion efficiency of ∼14.53%, but, after the CP treatment not much efficiency variation is observed. Whereas; the CP treatment is beneficial for medium/large pyramids (∼5–8 µm) based cells, which has enhanced the open-circuit voltage (45–63 mV) after smoothing/rounding of sharp peak/valley surfaces. But, we have observed a reduction in photocurrent due to an increase of light reflection from smoothened pyramid surfaces. Quantum efficiency analysis has provided the better insight with the silicon surface morphology dependent energy conversion. The cells’ reverse saturation currents also have analyzed to understand the silicon surface passivation and MoOx/n-Si junction quality. The performance variation of cells is explained by considering low-barrier shunts at the pyramids’ peaks/valleys, which influence the junction built-in potential at the depletion region.

Driving-in effect and gettering degradation induced by laser doping using borosilicate glass as dopant source

In the present work, driving-in effect with a low surface doping concentration and a deep junction after laser irradiation is illustrated by using borosilicate glass formed in the boron spin-on dopant diffusion process as dopant source. PC1D simulation results based on the experimental boron doping profiles demonstrate that the doping modification realized by laser irradiation can achieving an efficiency improvement of 0.13% at most. Meanwhile, no amorphous silicon and rare holes are observed after laser irradiation, indicating a relative low laser damage. Root mean square roughness is introduced to characterize the laser damage, whose variation trend with the laser frequency is opposite to that of effective minority carrier lifetime. Besides, unique gettering degradation effect by taking iron concentration as standard is observed, which is attributed to the re-dissolution and re-segregation process during laser irradiation. The present work will be helpful to deepen the understanding of laser boron doping as well as reduce the laser damage and relative high boron concentration induced by laser doping.

Thickness-modulated passivation properties of PEDOT:PSS layers over crystalline silicon wafers in back junction organic/silicon solar cells

PEDOT:PSS/silicon heterojunction solar cell has recently attracted much attention due to the fact that it can be simply and cost-effectively fabricated. It is crucial to suppress the interfacial recombination rate between silicon (Si) and organic film for improving device efficiency. In this study, we demonstrated a thickness-dependent passivation effect, i.e. the passivation quality over Si substrate was promoted dramatically with increasing the thickness of PEDOT:PSS layer. The effective minority carrier lifetime increased from 32 μs for 50 nm to 360 μs for 200 nm, which corresponds to a change in implied open circuit voltage (Voc-implied) from 545 to 635 mV. Back-junction hybrid solar cells featuring PEDOT:PSS films at rear side were designed to enable adoption of thick PEDOT:PSS layers without having to worry about parasitic absorption, showing a power conversion efficiency (PCE) of 16.3%. Combined with a proper pre-condition on the Si substrate, the back-junction hybrid solar cell with 200 nm PEDOT:PSS layer received an enhanced PCE of 16.8%. In addition, the improved long-term stability for the back-junction device was also observed. The PCE remained 90% (unsealed) after being stored in ambient atmosphere for 30 days and over 80% (sealed) after 150 days.

Deposition behaviour of metal impurities in acidic cleaning solutions and their impact on effective minority carrier lifetime in n-type silicon solar cells

Further increasing the conversion efficiency of silicon solar cells by advanced solar cell concepts like SHJ (Silicon Hetero-Junction), PERT (Passivated Emitter Rear Totally diffused), IBC (Interdigitated Back-Contact), requires a highly controlled silicon surface in terms of metal impurity density. The goal of this study is investigating the deposition property of different metals in acidic cleaning solutions and consequently determining the impact of these impurities on the effective minority lifetime of the crystalline silicon solar cell material. The deposition behaviour of impurities is mathematically described with an adsorption isotherm theory. Once attached at the silicon surface, the metal impurity can diffuse into the silicon bulk material during a high temperature process step like diffusion, passivation or contact annealing (firing).First, we have studied the adsorption isotherm behaviour of prominent metal impurities (Fe, Cu, Ti, Co, Cr and Zn) in acidic liquid onto a silicon surface. Moreover, the impact of metal impurities on effective minority carrier lifetime in commercially available n-type Cz-silicon (3–5 Ω cm, 239 cm2) is determined. From controlled contamination experiments we can extract an exchange volume, that provides the minimum amount on wet chemical cleaning solution that is required to clean a silicon surface from a given high metal impurity level to a specified low metal impurity level. This exchange volume plays a crucial role by defining feed and bleed recipes on wet chemical cleaning tanks in solar cell manufacturing. A second parameter extracted is the effective minority carrier lifetime degradation of the metal impurities. After deposition on the surface, the impurities are driven into the silicon bulk by high temperature processes. Depending on the lifetime degradation capacity, a relation of effective minority carrier lifetime versus surface contamination level could be identified for each metal impurity. We found Co, Fe and Cu having a strong impact on effective minority carrier lifetime degradation, e.g. 2e10/cm2 Fe surface concentration can reduce the effective minority carrier lifetime by 75%, while Ti, Zn and Cr are more moderate and only high surface concentrations above 1e12/cm2 lead to effective minority carrier lifetime degradation of more than 20% compared to the non-contaminated wafers.

Thermal atomic layer deposition of AlOxNy thin films for surface passivation of nano-textured flexible silicon

Aluminum oxynitride (AlOxNy) films with different nitrogen concentration are prepared by thermal atomic layer deposition (ALD) for flexible nano-textured silicon (NT-Si) surface passivation. The AlOxNy films are shown to exhibit a homogeneous nitrogen-doping profile and the presence of an adequate amount of hydrogen, which is investigated by Time-of-Fight Elastic Recoil Detection Analysis (ToF-ERDA). The effective minority carrier lifetimes are measured after the NT-Si surface passivation; the minimum surface recombination velocity (SRV) of 5 cm-s−1 is achieved with the AlOxNy film in comparison to the Al2O3 and AlN films (SRV of 7–9 cm-s−1). The better SRV with AlOxNy film is due to the collective effect of field-effect passivation by the presence of fixed negative charges, and chemical passivation by the presence of hydrogen within the film. The capacitance-voltage, and conductance measurements also are carried out using metal-oxide-semiconductor structure to determine the fixed negative charge density (Ni,ox), and defect density of states (Dit) in the AlOxNy films. The better surface passivation is attributed to unusually large Ni,ox of ~6.07 × 1012 cm−2, and minimal Dit of ~1.01 × 1011 cm−2-eV−1 owing to the saturation of Si dangling bonds by the hydrogen within the AlOxNy film matrix after the annealing step.

Assessing the Impact of Thermal Profiles on the Elimination of Light- and Elevated-Temperature-Induced Degradation

Light- and elevated-temperature-induced degradation (LeTID) in p-type multicrystalline silicon has a severe impact on the effective minority carrier lifetime of silicon and remains a crucial challenge for solar cell manufacturers. The precise cause of the degradation is yet to be confirmed; however, several approaches have been presented to reduce the extent of degradation. This paper presents insights on the impact of thermal budgets and cooling rates during post-firing illuminated anneals and their role in changing the lifetime and mitigating LeTID for thermal processes between 350 and 500 °C. We demonstrate that the thermal budget of these processes plays a crucial role in LeTID suppression and that the cooling rate only plays a role during short treatment durations (≤1 min). For the parameter space studied, we show that annealing for an appropriate time and temperature can both enhance the minority carrier lifetime and completely suppress the LeTID, with the injection-dependent Shockley–Read–Hall lifetime analysis indicating that the recombination activity of the LeTID defects in the bulk has been eliminated. Finally, this paper demonstrates a process that results in a stable lifetime after 800 h of conventional light-soaking at 75 °C.

Improved amorphous/crystalline silicon interface passivation for silicon heterojunction solar cells by hot-wire atomic hydrogen during doped a-Si:H deposition

Intrinsic/doped stacked hydrogenated amorphous silicon (a-Si:H) are widely used passivation layers for amorphous/crystalline silicon (a-Si/c-Si) heterojunction solar cells. This work reports that hot wire chemical vapor deposition of doped a-Si:H can significantly modify the property of the underlying intrinsic a-Si:H (a-Si:H(i)) as well as a-Si/c-Si interface passivation, which stems from the in-diffusion of highly reactive atomic hydrogen. Fourier transform infrared spectroscopy, spectroscopic ellipsometry and Raman analyses indicate that the underlying a-Si:H(i) films become more compact and less defected as a result of network reconstruction during doped a-Si:H capping. After this reconstruction, underdense a-Si:H(i) films obtained superior passivation quality than widely used dense layers, despite the inferior quality in the initial state. Effective minority carrier lifetime of c-Si passivated by underdense a-Si:H(i) was 19.9 ms, much higher than 15.2 ms in the case of using dense a-Si:H(i). The porous structure of underdense a-Si:H(i) facilitates hydrogen diffusion towards a-Si/c-Si interface and hence a rapid reduction of interface defect densities occurs, accounting for the better passivation quality. SHJ solar cells (160 μm, 156 × 156 mm2) with industry-compatible process were fabricated, yielding the efficiency up to 23.0% with high Voc values of 741 mV.

Damage to passivation contact in silicon heterojunction solar cells by ITO sputtering under various plasma excitation modes

Analysis of damage to passivation contact in heterojunction with intrinsic thin layer (HIT) solar cells by indium tin oxide (ITO) sputtering under various plasma excitation modes such as radio frequency (RF), direct current (DC), RF-superimposed DC, pulsed DC is presented. A significant degradation of effective minority carrier lifetime of the precursor cells at both low and high-level injections after the ITO deposition by sputtering technique was observed regardless of plasma excitation modes. We found that the main reason for this degradation was mainly due to the ion flux in the sputtering plasma rather than the ion kinetic energy. On the basis of the experimental and simulated results, we attributed the degradation of surface passivation quality mainly to the damage of the amorphous-silicon/crystalline-silicon interfaces rather than that of the intrinsic hydrogenated amorphous silicon layers. This degradation could be significantly reduced by the ITO deposition at a high temperature in which a trade-off between degradation and curing step was expected to occur. The cell performance of the HIT solar cells using the ITO films deposited by various plasma excitation modes at 180 °C was subsequently discussed. The ITO films deposited by the RF-superimposed DC mode exhibited a high potential as excellent opto-electrical properties and free sputter-induced damage electrodes for HIT solar cell applications. To our best knowledge, this is the first time that the ITO films deposited by the RF-superimpose DC mode are used as electrodes in the HIT solar cells.

Vacuum-Free, Room-Temperature Organic Passivation of Silicon: Toward Very Low Recombination of Micro-/Nanotextured Surface Structures.

Crystalline silicon (c-Si) solar cells remain dominant in the photovoltaic (PV) market because of their cost-effective advantages. However, the requirement for expensive vacuum equipment and the power-hungry thermal budget for surface passivation technology, which is one of the key enablers of the high performance of c-Si solar cells, impede further reductions of costs. Thus, the omission of the vacuum and high-temperature process without compromising the passivation effect is highly desirable due to cost concerns. Here, we demonstrate a vacuum-free, room-temperature organic Nafion thin-film passivation scheme with an effective minority carrier lifetime (τeff) exceeding 9 ms on an n-type c-Si wafer with a resistivity of 1-5 Ω·cm, corresponding to an implied open circuit voltage (i Voc) of 724 mV and upper-limit surface recombination velocity (SRV) of 1.46 cm/s, which is a level that is in line with the hydrogenated amorphous Si film-passivation scheme used in the current PV industry. We find that the Nafion film passivation of Si can be enhanced in an O2 atmosphere and that the Nafion/c-Si interface oxidation should be responsible for the passivation mechanism. This highly effective passivation is also achieved on various micro-/nanotextured Si surface structures from actual production, including a pyramidal surface and nanopore-pyramid hybrid structure with nanopores on the inclined plane of the pyramid. We develop an organic Nafion-passivated n-type back-junction Si solar cell to examine application in a real device. The open circuit voltage ( Voc) of the solar cell with the Nafion passivation layer achieves a clear improvement (30.8 mV) over those without the passivation layer, resulting in an increase (1.5%) in the power conversion efficiency. These results suggest the potential use of these organic electronics with current Si microelectronics and a new strategy for the development of vacuum-free, low-temperature Si-based PVs at low cost.

Light harvesting and effective surface passivation using electrodeposited Y2O3 for broadband absorption enhancement in silicon solar cells

This paper reports investigation on passivation properties of electrodeposited yttrium oxide Y2O3 thin films on monocrystalline silicon substrate. We examined its application as an effective light harvesting and a passivation layer to enhance the electrical properties of the processed solar cell. We found that the deposited Y2O3 thin film is excellent antireflection coating and post deposition sintering acts to passivate the coated monocrystalline silicon substrate. Next, the coated substrates were annealed at various temperatures for a short duration. The crystallinity of the deposited yttrium oxide thin film was analyzed by means of X-ray diffraction. The latter shows an obvious dependence with the annealing temperature. Surface morphology was examined by a field emission scanning electron microscope and revealed a high tendency for light scattering through its particular morphology, essentially after post-annealing at 650 °C. The effective minority carrier lifetime measurements, using a WTC-120 photoconductance lifetime tester, show an obvious increase indicating the vital role of yttrium oxide on the passivation of the front surface. The electrical properties were studied using the Hall effect and the Van Der Pauw methods to measure the resistivity and mobility of the majority carriers. The effect of the deposited thin film on the optoelectronic properties was evaluated by means of the internal quantum efficiency that was improved noticeably, proving a large decrease of the recombination activities mainly at the front surface. These results show clearly that the deposited layer has a double effect: a passivating layer and an antireflective layer increasing the light trapping at the front side of the processed silicon solar cell.

Dry Passivation Process for Silicon Heterojunction Solar Cells Using Hydrogen Plasma Treatment Followed by <italic>In Situ</italic> a-Si:H Deposition

A fully dry and hydrofluoric-free low-temperature process has been developed to passivate n-type crystalline silicon (c-Si) surfaces. Particularly, the use of a hydrogen (H2) plasma treatment followed by in situ intrinsic hydrogenated amorphous silicon (a-Si:H) deposition has been investigated. The impact of H2 gas flow rate and H2 plasma processing time on the a-Si:H/c-Si interface passivation quality is studied. Optimal H2 plasma processing conditions result in the best effective minority carrier lifetime of up to 2.5 ms at an injection level of 1 × 1015 cm−3, equivalent to the best effective surface recombination velocity of 4 cm/s. The reasons that enable such superior passivation quality are discussed in this paper based on the characterization of the a-Si:H/c-Si interface and c-Si substrate using transmission electron microscopy, high angle annular dark field scanning transmission electron microscopy, and deep-level transient spectroscopy.

Beneficial Effect of Two-Step Annealing via Low Temperature of Vacancy Complexes in N-type Czochralski Silicon

We report a simple, time-saving and effective low-temperature approach to avoid the effect of intrinsic defects in n-type Czochralski silicon (Cz-Si) wafers. This approach consists of submitting Cz-Si wafers to two annealing steps. The first annealing step was conducted in the temperature range 100–200°C to dissociate phosphorus–vacancy (P-V) defects. These defects were identified through the calculation of its activation energy (Ea) of annihilation. The second annealing step was conducted in the temperature range 300–400°C to eliminate defects caused by vacancy–oxygen (V-O) pairs. The deactivation effect of the V-O pairs was highlighted using Fourier transform infrared spectroscopy and the effective minority carrier lifetime (τeff). By combining these two annealing steps, we succeeded in enhancing τeff from 180 to 2400 μs and the electrical parameters of the silicon solar cell.

The impact of indium tin oxide deposition and post annealing on the passivation property of TOPCon solar cells

In this paper, the influence of indium tin oxide (ITO) deposition on the passivation quality of tunnel oxide passivated contact solar cells was investigated. Both phosphorous-doped poly-Si/SiOx (n-TOPCon) and boron-doped poly-Si/SiOx (p-TOPCon) stacked films were fabricated on crystalline Si substrate, and ITO thin films were deposited by radio frequency (RF) magnetron sputtering system with various temperatures and RF powers, followed by post annealing. Effective minority carrier lifetime (τeff) of all the samples degraded drastically after ITO deposition. After post annealing, τeff of p-TOPCon samples exhibited significant recovery, while τeff of n-TOPCon samples only recovered partially. In addition, the deposition of ITO at lower RF power or room temperature leads to more effective recovery of τeff. The τeff recovery after ITO deposition thus depends on the types of TOPCon, which may be related to the film quality improvement of poly-Si during the post-annealing. The conversion efficiency of the top/rear TOPCon solar cells was decreased severely due to the sputtering damage during ITO deposition, and it can be improved by post-annealing at relatively high temperature.