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Laser Assisted Patterning of a‐Si:H: Detailed Investigation of Laser Damage
Author(s) -
Xu Menglei,
Bearda Twan,
Radhakrishnan Hariharsudan S.,
Filipič Miha,
Gordon Ivan,
Debucquoy Maarten,
Szlufcik Jozef,
Poortmans Jef
Publication year - 2017
Publication title -
physica status solidi (rrl) – rapid research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.786
H-Index - 68
eISSN - 1862-6270
pISSN - 1862-6254
DOI - 10.1002/pssr.201700125
Subject(s) - materials science , passivation , laser , silicon , etching (microfabrication) , layer (electronics) , laser ablation , substrate (aquarium) , optoelectronics , amorphous silicon , amorphous solid , irradiation , scanning electron microscope , isotropic etching , transmission electron microscopy , heterojunction , crystalline silicon , optics , nanotechnology , composite material , chemistry , crystallography , oceanography , physics , geology , nuclear physics
A detailed investigation of the laser damage to amorphous silicon (a‐Si:H) layers patterned by laser ablation (LA) and wet chemical etching is presented. This approach can be applied to pattern the rear side of silicon heterojunction interdigitated back‐contact solar cells. Only the top sacrificial a‐Si:H laser‐absorbing layer of an a‐Si:H/SiO x /a‐Si:H/c‐Si stack is ablated. Laser damage in the bottom a‐Si:H layer and a‐Si:H/c‐Si interface is analyzed by both scanning electron microscopy and transmission electron microscopy. We show that the a‐Si:H/c‐Si passivation is degraded by laser damage and that this degradation can be diminished by increasing laser processing speed. This is attributed to a decrease of laser‐irradiated area, and particularly smaller overlapping zones of adjacent laser pulses. The re‐passivation quality after LA and wet etching is similar to that of as‐passivated samples. This indicates that laser damage is not present in the bulk c‐Si substrate but only in the a‐Si:H passivation layer, which is removed during subsequent wet etching, thus allowing high quality repassivation.