Determination of the conduction band offset in the A-Si:H/C-Si heterojunction structures from coplanar temperature current-voltage measurements

The conductance of electron rich inversion layer at the a-Si:H(n)/c-Si(p) interface was measured at various temperature and an activation energy was evaluated from Arrhenius plot. Strong dependence of calculated and measures activation energy on the band offset at the hetero-junction allowed us to determine the conduction band offset in the studied sample ΔE_C = 170 meV. Considering this value and assuming low defect density at the interface we were able to estimate performance of solar cell with one a-Si:H(n)/c-Si(p) hetero-junction prepared under similar conditions as our sample. The open circuit voltage of such solar cell is V_OC = 0.620 V and the efficiency is η = 15.2%. Increasing the conduction band offset, decreasing the defect density at the interface and improving the light management in the solar cell can attain further increasing of efficiency. (authors)