Metalorganic chemical vapor deposition growth of InN for InN/Si tandem solar cell

Abstract

A new tanden solar cell having an InN top cell is proposed since InN is a binary material having a bandgap of about 1.9 eV suitable for a top cell in a 2-junction tandem cell. An estimation of the conversion efficiency of InN/Si tandem cell has been made. For a 2-terminal cell, the bandgap of InN, 1.95 eV, is close to the optimum for AM 0 illumination because currents between top and bottom cells can be matched. The MOCVD growth of InN has been studied as a key technology for device fabrication. Epitaxial growth of InN directly on Si using the MOCVD technique is unsuccessful because of the formation of an amorphous SiN_x layer on the Si substrate surface. Characterization has been made for single-crystalline InN films grown on α-Al₂O₃ substrates. Compared with InN films grown at a reduced pressure (≈ 76 Torr), those grown at the atmospheric pressure have a lower background carrier concentration and a higher electron mobility, although thier surface morphology and crystallographic quality are somewhat worse.