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Hydrogen related phenomena at the ITO/a‐Si:H/Si heterojunction solar cell interfaces
Author(s) -
Ulyashin Alexander,
Sytchkova Anna
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.201200459
Subject(s) - materials science , indium tin oxide , solar cell , heterojunction , nanotechnology , optoelectronics , hydrogen , silicon , layer (electronics) , chemical engineering , chemistry , organic chemistry , engineering
Properties of thin a‐Si:H and indium‐tin oxide (ITO) layers as well as properties of interfaces of Si based heterojunction (HJ) ITO/(p)a‐Si:H/n‐Si structures were analyzed by means of atomic force microscopy (AFM) and scanning spreading resistance microscopy. It is shown that the morphology of thin ITO layers grown on n‐type polished crystalline Si or on (p)a‐Si:H/n‐Si substrates depends on the deposition temperature and has peculiarities on nano‐scale. Formation of highly conductive nano‐dots on the surface and in the bulk of ITO layers is found. The observed nano‐spots and nano‐dots are attributed to the influence of hydrogen initiated reduction process, which occurs upon deposition of ITO films on an a‐Si:H layer during the fabrication process of a HJ solar cell. This fact is confirmed by investigation of morphological properties of ITO surfaces after treatment by hydrogen plasma. It is shown that formation of conductive nano‐particles on the ITO surface initiated by hydrogen does not change essentially transparency of an ITO layer. It is concluded that conductive nano‐dots at the ITO/a‐Si:H interface can be considered as local conductive channels, which provide a current flow through the ITO/(p)a‐Si:H interface without essential shadowing of the solar cell structure. This finding opens an interesting way for the optimization of properties of the ITO/Si‐based HJ solar cells.