Optimization of p-Type Hydrogenated Microcrystalline Silicon Oxide Window Layer for High-Efficiency Crystalline Silicon Heterojunction Solar Cells

Abstract

Wide-gap, high-conductivity p-type hydrogenated microcrystalline silicon oxide (p-mc-SiO:H) films deposited by very high frequency plasma-enhanced chemical vapor deposition (60 MHz VHF-PECVD) at a low substrate temperature of approximately [200 C] were used as window layers in n-type crystalline silicon (n-c-Si) heterojunction (HJ) solar cells. We investigated the effect of p-mc-SiO:H window layer thickness on HJ solar cells by changing deposition time and silane (SiH 4 ) flow rate. The effects of carbon dioxide flow rate on the p-mc-SiO:H window and i-a-SiO:H buffer layer were also studied. Employing a p-mc-SiO:H/i-a-SiO:H/n-c-Si [Czochralski (CZ), 200 mm, (100)]/ i-a-Si:H/n-a-Si:H configuration, we achieved an efficiency of 17.8% (active area efficiency) with an open-circuit voltage (V oc ) of 665 mV. The solar cells showed a spectral response of about 0.83 at a wavelength of 400 nm, which is higher than that of conventional HJ solar cells with amorphous silicon window layers.

Resolving the nanostructure of plasma-enhanced chemical vapor deposited nanocrystalline SiOx layers for application in solar cells

“…[1][2][3] Since the electrical and optical parameters of the material are tunable within a wide range, 4 several other applications for solar cells have been explored. The material has been used as a transparent n-type 5 or p-type contact for heterojunction, 6,7 and thin-film silicon solar cells [8][9][10][11] or as a dielectric layer in back reflectors for a thin film single-junction 12 or doublejunction solar cells. 13 For several years, spinodal decomposition of a-SiO x layers by thermal annealing was used to fabricate silicon nanocrystals (nc-Si) in a silicon-dioxide matrix.…”

Improved hetero-interface passivation by microcrystalline silicon oxide emitter in silicon heterojunction solar cells

“…This trend of I TA /I TO reveals that the n-lcSiO x :H evolves from amorphous to crystalline phase with an increasing n-lc-SiO x :H deposition time. The n-lc-SiO x :H thin film presents a highly disordered structure at the initial growth stage due to the disordered structure in i-a-SiO x :H passivation layer [15,19]. This results in the amorphous phase structure of the deposited n-lc-SiO x :H film.…”

“…At the initial deposited stage of the lc-SiO x :H emitter on the intrinsic a-SiO x :H buffer layer, a less crystalline incubation layer normally forms. As a consequence, the doping efficiency and dark conductivity of the deposited lc-SiO x :H emitter decrease, thus it limits the passivation at heterointerface as well as solar cells performance [6,15,19]. Hence, to obtain excellent heterointerface passivation as well as high-efficiency SHJ solar cell, we need to investigate the growth process of n-lc-SiO x :H emitter layer and study the connection between the preparation process and the heterointerface passivation in SHJ solar cells.…”

Effect of Oxygen and Diborane Gas Ratio on P-type Amorphous Silicon Oxide films and Its Application to Amorphous Silicon Solar Cells

“…In contrast, p-type a-SiO x :H films have a lower defect density, Urbach energy and comparatively high doping efficiency [2]. Therefore, the p-type a-SiO x :H films provide a wide bandgap and higher photoconductivity compared to other wide bandgap hydrogenated amorphous silicon materials, which could be useful as a window layer for the solar cells [1,[3][4].…”