Phosphorus-doped polysilicon passivating contacts deposited by atmospheric pressure chemical vapor deposition

Abstract

In this work, we present a high quality tunnel oxide passivating, electron-selective contact that is formed using an in-situ phosphorus-doped polycrystalline silicon (poly-Si) layer deposited using an in-line atmospheric pressure chemical vapor deposition (APCVD) process. In-line APCVD is a single-sided deposition process that does not require vacuum systems and is well suited for high volume manufacturing. To fabricate this tunnel oxide passivating contact (TOPCon), we deposit an amorphous silicon (a-Si) layer on silicon oxide (SiO) passivated n-type crystalline silicon (c-Si) followed by an annealing step at around 910 ∘C, which provides solid phase crystallization. The contact shows an excellent surface passivation quality with an effective minority carrier lifetime of ≈4.2 ms and an implied open circuit voltage (iV ) of ≈717 mV after annealing without any additional hydrogenation process. Saturation current density (J ) of ≈18 fA cm−2 is recorded for this contact. Contact resistivity () of ≈50 mΩ·cm−2 and junction resistivity of ≈0.24 Ω·cm−2 are realized with e-beam evaporated aluminium (Al) metal contact.

Process–Structure–Properties Relationships of Passivating, Electron‐Selective Contacts Formed by Atmospheric Pressure Chemical Vapor Deposition of Phosphorus‐Doped Polysilicon

“…Chemical passivation improvement emerges from the reorientation of the SiO x bonding at the interface at this temperature. [ 39 ] Moreover, increased active dopant concentration in the poly‐Si layer and dopant diffusion (Figure 2a) through the SiO x layer into the c‐Si increase the band bending at the interface [ 24 ] and thus enhance the field‐effect passivation. The combination of these mechanisms provides this excellent surface passivation after annealing at 850 °C for 30 min.…”

“…The deposition process has been explained in detail previously. [ 24 ] Different PH 3 gas ratios and deposition temperatures ( T d ) (Table 1) were used to deposit the doped Si layer to observe their effect on the microstructure, electrical properties, and passivation quality of the contacts. Batches A, B, and C in Table 1 were deposited in the same deposition zone temperature of 695 °C using different PH 3 ratios of 1.48%, 4.00%, and 9.09%, respectively.…”

“…A high‐quality passivating, electron‐selective contact fabricated using APCVD in situ P‐doped poly‐Si film and thin thermally grown SiO x layer was reported in a previous study. [ 24 ] In this work, we present a passivating electron‐selective contact fabricated with APCVD in situ P‐doped poly‐Si layer on top of a thin SiO x layer grown using deionized water with dissolved ozone (DI–O 3 ). [ 4,25 ] Additionally, the influence of the deposition process and annealing process parameters on the microstructure, electrical properties, and passivation quality of the contact is reported, providing guidance on the optimal fabrication process for the APCVD‐based poly‐Si electron contacts.…”

“…Finally, by the better understanding of the process-structure-properties relationship of the contact, we can achieve even lower saturation current density ( J 0 ) and junction resistivity compared to the previous work. [24] 2. Results and Discussion…”

Effect of glass frit composition on reliability of silver paste metallization in crystalline silicon solar cells

“…The development of photovoltaic (PV) industry has been constantly pursuing more efficient, cheaper, and more reliable solar cells [1][2][3]. With the development and application of advanced manufacturing technology, more complex and efficient crystalline silicon (c-Si) cell, such as tunnel oxide passivated contact (TOPCon) cells and back contact (BC) cells [4] are being pushed to the market and become mainstream products [5][6][7]. Through measures such as large-scale manufacturing, improving production efficiency, and using cheaper raw materials, the cost of PV power generation has approached or been lower than that of traditional energy generation [8].…”