Optimization of Amorphous Silicon Oxide Buffer Layer for High-Efficiency p-Type Hydrogenated Microcrystalline Silicon Oxide/n-Type Crystalline Silicon Heterojunction Solar Cells

Abstract

Intrinsic hydrogenated amorphous silicon oxide (i-a-SiO:H) films deposited by very high frequency plasma-enhanced chemical vapor deposition (60 MHz VHF-PECVD) at a low substrate temperature of approximately 200 °C were used as a front buffer layer in p-type hydrogenated microcrystalline silicon oxide/n-type crystalline silicon (p-µc-SiO:H/n-c-Si) heterojunction solar cells. We found that the oxygen concentration in the i-a-SiO:H buffer layer strongly affected the solar cell performance and that the short wavelength response in quantum efficiency (QE) was improved by oxygen addition. Employing a p-µc-SiO:H/i-a-SiO:H/n-Si [Czochralski (CZ), 200 µm, (100)]/i-a-Si:H/n-a-Si:H/Ag/Al configuration, we achieved an efficiency of 17.9% with Voc of 671 mV.