Liu Bangwu

Influence of annealing temperature on passivation performance of thermal atomic layer deposition Al2O3 films

Chemical and field-effect passivation of atomic layer deposition (ALD) Al2O3 films are investigated, mainly by corona charging measurement. The interface structure and material properties are characterized by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS), respectively. Passivation performance is improved remarkably by annealing at temperatures of 450 °C and 500 °C, while the improvement is quite weak at 600 °C, which can be attributed to the poor quality of chemical passivation. An increase of fixed negative charge density in the films during annealing can be explained by the Al2O3/Si interface structural change. The Al—OH groups play an important role in chemical passivation, and the Al—OH concentration in an as-deposited film subsequently determines the passivation quality of that film when it is annealed, to a certain degree.

Realization of conformal doping on multicrystalline silicon solar cells and black silicon solar cells by plasma immersion ion implantation

Emitted multi-crystalline silicon and black silicon solar cells are conformal doped by ion implantation using the plasma immersion ion implantation (PIII) technique. The non-uniformity of emitter doping is lower than 5%. The secondary ion mass spectrometer profile indicates that the PIII technique obtained 100-nm shallow emitter and the emitter depth could be impelled by furnace annealing to 220 nm and 330 nm at 850 °C with one and two hours, respectively. Furnace annealing at 850 °C could effectively electrically activate the dopants in the silicon. The efficiency of the black silicon solar cell is 14.84% higher than that of the mc-silicon solar cell due to more incident light being absorbed.

AlOx prepared by atomic layer deposition for high efficiency-type crystalline silicon solar cell

The influence of atomic layer deposition parameters on the negative charge density in AlOx film is investigated by the corona-charge measurement. Results show that the charge density can reach up to −1.56 × 1012 cm−2 when the thickness of the film is 2.4 nm. The influence of charge density on cell conversion efficiency is further simulated using solar cell analyzing software (PC1D). With AlOx passivating the rear surface of the silicon, the cell efficiency of 20.66% can be obtained.