Fabrication of AgGaTe₂ Solar Cells Using GaTe Powder to Suppress Mo–Te Compounds Formation near the Electrode Layer

AgGaTe₂ is an attractive material for the light-absorbing layer in solar cells and has been deposited by close-spaced sublimation using Ga₂Te₃ powder source. However, the samples exhibit an excess of Te, as well as undesired Mo–Te compounds, when AgGaTe₂ is deposited on Mo/glass substrates. Therefore, the AgGaTe₂ light-absorbing layer is deposited using an Ag₂Te and GaTe mixed powder source and examined herein. By replacing the Ga₂Te₃ source with GaTe, the Te content confirmed by the X-ray fluorescent has significantly decreased. Cross-sectional transmission electron microscopy observation indicates that the formation of Mo–Te compounds is suppressed. This is because Ga₂Te₃ produces additional Te gas in the initial decomposition reaction during deposition, and GaTe does not. In addition, the J–V curves show an improved conversion efficiency for solar cells fabricated using GaTe.