Room temperature H2 plasma treatment for enhanced passivation of silicon/TiO2 interface

Abstract

Simultaneous requirement of excellent interface passivation and low thermal budget is a desirable feature for low cost Si based carrier selective solar cells. Accordingly, Titanium dioxide (TiO2), a widely used electron selective material, finds challenges related to thermal annealing like phase change and compatibility with thermal budget of hole transport layers. To address this, here we report a H2 plasma treatment process at room temperature which significantly reduces the surface recombination velocity (∼40 cm/s). Consequently, the reverse saturation current of the Si-TiO2 diode improves by a factor of 40, built-in potential improves by 100 mV, and the diode exhibits a near unity ideality factor. Using the same method, our Si-based double heterojunction solar cell results in an absolute increase of 2.4% in efficiency over devices with conventional thermal annealing. Given the ease of implementation and excellent performance, the proposed method is a promising alternative to thermal annealing for Si based heterojunction devices.

Novel Boron-Doped p-Type Cu2O Thin Films as a Hole-Selective Contact in c-Si Solar Cells

“…Additionally, these materials can be deposited by simple techniques like sputtering, evaporation, and solution process . TMOs like MoO 3 , V 2 O 5 , WO 3 , and NiO x and certain organic materials like PEDOT:PSS and PEDOT:PSS-CNT composites have been explored as a hole-selective layer (HSL). ,, Besides TMOs, TiO 2 , ZnO, alkali metal fluorides like MgF 2 and LiF, and specific organic dipole molecules (e.g., PEO) can be used as electron-extracting layers. ,− These compounds, which are used as selective contacts, are generally n-type in nature. Carrier-selective hole conducting p-type oxides like copper oxide and nickel oxides are the less investigated ones, of which the copper oxide is a well-known metal oxide having no toxicity, high chemical stability, and abundant reserves and have been used in various other optoelectronic applications .…”

Dopant‐free passivating contacts for crystalline silicon solar cells: Progress and prospects

“…182,201 Hydrogen plasma treatment (HPT) is another hydrogenation method to improve the passivation of the interface. 202 With HPT, hydrogen atoms can diffuse to the c-Si surface more efficiently and quickly, thus saturating the dangling bonds and decreasing J 0c of the passivating contact. Miyagawa et al investigated the HPT effect on the passivation quality of the ALD-TiO x /c-Si structure.…”

Improved Performance of Titanium Oxide/Silicon Oxide Electron‐Selective Contacts by Implementation of Magnesium Interlayers

“…The passivation performance of the TiO x has been improved by postdeposition annealing, [12][13][14][15][16][17] inserting silicon oxide interlayer, [12][13][14][15][16][17] and hydrogen plasma treatment. [11,[18][19][20] The origin of the improved passivation performance is plausibly caused by the formation of Si─O─Ti bonds, [16,21,22] hydrogenation of dangling bonds on the Si surface, [11,[18][19][20] and enhanced band bending by trapped electrons in TiO x . [23] Electron transport at contacts/TiO x /c-Si heterointerface is one of the issues to be solved due to relatively high contact resistivity over 100 mΩ cm 2 .…”