Carrier transport through boron-doped amorphous diamond-like carbon p layer of amorphous silicon based p-i-n solar cells

Abstract

The current transport mechanisms in boron-doped amorphous diamond-like carbon (p-a-DLC:H) used as part of the p layer of hydrogenated amorphous silicon (a-Si:H) solar cells are investigated by studying the temperature dependence of the dark current-voltage characteristics of the solar cell. The cell structure is glass/SnO2/p-a-DLC:H/p-a-SiC:H/i-a-Si:H/n-mu c-Si:H/Al. The temperature dependence of the reverse saturation current and the ideality factor shows that carriers transport dominantly over the p-a-DLC:H by thermionic emission at higher temperatures above about 300 K and through the tunneling process by a hopping mechanism in the p-a-DLC:H at lower temperatures. Using the Schottky barrier model, it is shown that the lowering of the Schottky barrier height by inserting the interfacial p-a-DLC:H between the SnO2 and p-a-SiC:H causes the open circuit voltage and the short wavelength response of the cells to be enhanced. (C) 1999 American Institute of Physics. [S0003-6951(99)01730-1].