SIGNIFICANCE OF TUNNELING IN P(-SILICON CARBIDE N-CRYSTALLINE SILICONHETEROJUNCTION SOLAR-CELLS() AMORPHOUS)

We used the internal photoemission (IPE) technique to accurately deter mine the valence and conduction band offsets at the a-SiC:H/c-Si inter face and investigated with numerical simulations their effects on the photocarrier collection in p(+) a-SiC:H/n c-Si heterojunction solar ce lls. The valence and conduction band discontinuities were found to be 0.60 and 0.55 eV, respectively. However, despite the large barrier at the valence band edge, 30 nm p(+) a-SiC:H/n c-Si heterojunction solar cells show no collection problems due to blocking of holes (FF=0.73). Combined IPE measurements and simulation results indicate that tunneli ng of holes through this barrier at the valence band edge can explain the unhindered collection. (C) 1998 American Institute of Physics. [S0 003-6951(98)00844-4].