Heating the earth-shield instead of the anode reduces metastable defects in plasma deposited Amorphous Silicon Solar Cells

Amorphous silicon (a-Si) is used in a variety of commercial devices. One common factor causing performance issues in these devices is metastability which has been investigated for over 40 years. Here we use the idea that increased gas temperature reduces the electron temperature in the plasma. This decreases silylene radical generation and hence formation of higher silanes, that have been associated with metastable defect formation. Increasing the gas temperature near the cathode by heating of the earth-shield, while keeping the substrate, on which the material is deposited, at the same temperature, reduces metastability in solar cells, relative to state-of-the-art hydrogen-dilution deposited devices. We suggest that taking this process to its logical extension – cooling the anode to keep the substrate temperature constant while further increasing the gas temperature near the cathode, would practically eliminate metastability in the material. That breakthrough would significantly improve the efficiency of a-Si based multijunction cells. • Heating the earth shield instead of the anode reduces metastable defects in a-Si solar cells. • Higher temperatures near the cathode suppress formation of silylene relative to silyl radicals. • Stable fill factors of a-Si solar cells are improved using earth-shield heating. • Stable a-Si solar cells can be made by heating the earth shield and cooling the substrate. • a-Si solar cell performance deposited at lower than optimum substrate temperatures can be improved with earth-shield heating.