The charge transport properties of a-Si:H thin films under hydrostatic pressure

Time resolved thermoelectric effects (TTE) were used to simultaneously determine trap levels and trap state density differences in amorphous (a-Si:H) samples. In particular, the trap state density differences are obtained from the decay of the ambipolar charge distribution, i.e. stage 2 of the TTE transients. The trap state difference density is measured under hydrostatic pressures, up to 2.2 kbar. The trap state density difference changes from a negative peak to a positive peak with increasing hydrostatic pressure, suggesting a significant pressure induced shift of the electron and hole trap levels.