N-GaP/p-Si heterojunction solar cells fabricated by PE-ALD

Abstract

Significant progress in photovoltaic conversion of solar energy can be achieved by new technological approaches that will improve the efficiency of solar cells and make them appropriate for mass production. A new technological approach for the growth of III-V compounds on Si substrates using low temperature plasma-enhanced atomic layer deposition (PE-ALD) is explored in the paper. This technique, which consists of alternatively changing the phosphorus and gallium atom source flows providing the growth of one monolayer by cycle, was developed for the growth of GaP films on Si substrates in a standard PECVD setup at 380 °C using PH3 and TMG (Trimethylgallium) as sources of III and V atoms. First (n)GaP/(p)c-Si anisotype heterojunction solar cell structures fabricated by PE-ALD exhibit open circuit voltage values similar to that obtained for (n)a-Si:H/(p)c-Si heterojunctions fabricated using the same (p)c-Si substrates. However (n)GaP/(p)c-Si solar cells demonstrates a potential to extend a high quantum efficiency in the short wavelength region due to lower absorption losses in the GaP emitter layer.