Innovative Wide-Spectrum Mg and Ga-Codoped ZnO Transparent Conductive Films Grown via Reactive Plasma Deposition for Si Heterojunction Solar Cells

Abstract

In this work, wide-spectrum Mg- and Ga co-doped ZnO (MGZO) transparent conductive films are developed via reactive plasma deposition (RPD) technique with soft thin-film growth process. MGZO film with a work function of ~4.36 eV can be achieved within 12 min without any intentional substrate-heating treatment. 480nm-thickness MGZO film exhibits a low resistivity of ~9.9x10-4 Ωcm and a high transmittance of ~82.6% in the UV-VIS-NIR region (λ approximately 400 nm-1200 nm). XRD spectra show that MGZO films exhibit (103) preferred orientation as the film thickness increases. A silicon hetero-junction (SHJ) solar cell based on 480nm-thick MGZO at the front side is completed. Excellent continuity of MGZO film is proven by the cross-sectional SEM images and there are no cracks and pinholes on the top and bottom of the c-Si pyramids. Further efficiency improvements are achieved using an ultra-thin SnOx buffer layer with an ameliorated p-a-Si:H/TCO interface. Also, a silicon hetero-junction (SHJ) solar cell using M...