Wide Band-Gap Silicon Based Layers for Heterojunction Solar Cells

Abstract

In amorphous/crystalline silicon heterojunction (SHJ) solar cells, optical losses can be reduced by replacing the amorphous silicon thin films with wide bandgap (WBG) amorphous silicon based thin layers, such as oxygen-alloyed amorphous silicon (a-SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> :H), oxygen-alloyed nano-crystalline silicon (μc-SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> :H), or carbon-alloyed amorphous silicon (a-SiC <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> :H) materials. In this paper, we applied hydrogen (H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) plasma treatment to the WBG layer deposition. The average short circuit current (JSC) of the SHJ solar cells with H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -treated passivation layers is increased by 0.24 mA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> without open circuit voltage (VOC) or fill factor (FF) drop, suggesting that good interface passivation is maintained. Additionally, nano-crystalline oxygen-alloyed silicon (μc-SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> :H) layer is deposited as window layer for further increase in JSC by more than 0.4 mA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .