Premium
In situ excimer laser irradiation as cleaning tool for solid phase epitaxy of laser crystallized polycrystalline silicon thin films
Author(s) -
Höger Ingmar,
Schmidt Thomas,
Landgraf Anja,
Schade Martin,
Gawlik Annett,
Andrä Gudrun,
Leipner Hartmut S.,
Falk Fritz
Publication year - 2013
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201330056
Subject(s) - materials science , epitaxy , silicon , excimer laser , amorphous solid , polycrystalline silicon , deposition (geology) , layer (electronics) , amorphous silicon , analytical chemistry (journal) , crystalline silicon , optoelectronics , chemical engineering , laser , nanotechnology , optics , crystallography , chemistry , organic chemistry , physics , thin film transistor , paleontology , engineering , sediment , biology
This study demonstrates an innovative approach to clean a polycrystalline seed layer surface for solid phase epitaxy of amorphous silicon (a‐Si). The excimer laser cleaning (ELC) makes use of in situ excimer laser irradiation during the first stages of a‐Si deposition leading to melting of the as deposited a‐Si and parts of the seed layer. The increased diffusion in liquid silicon allows for “smearing out” of surface contamination species. After liquid phase epitaxy is finished, further a‐Si is deposited and crystallized by solid phase epitaxy. Thanks to the “smearing out,” the interface between the crystalline and amorphous silicon exhibits less contamination locally. SIMS measurements demonstrate a reduced carbon concentration at the seed layer surface after ELC. Numerical simulations, taking into account heat transfer and temperature dependent diffusion, support the reduction of carbon concentration. The simulations agree very well with experimental results. To get optimal solid phase growth conditions, the a‐Si deposition temperature has to be below 200 °C. Above 200 °C deposition temperature, defective growth occurs resulting in poor crystallinity or even in nonepitaxial growth.