InAlAs epitaxial growth for wide band gap solar cells

We demonstrate high quality InAlAs epitaxial growth by metalorganic vapor phase epitaxy and wide band gap solar cell fabrication. X-ray diffraction and transmission electron microscopy were used to characterize the crystalline quality of the epitaxial InAlAs grown. InAlAs solar cells lattice-matched to InP were grown and electrically characterized under AM 1.5 global 1-sun illumination. Window layers with different composition and, therefore, band gap energies were used to compare its effect on the overall device performance. In order to improve the electrical contact at the top window (Al-rich), an InGaAs cap layer was used. The resulting first generation of InAlAs solar cells showed an efficiency higher than 14 %, open circuit voltage of V_oc = 1 V, J_sc = 19.3 mA/cm², and maximum external quantum efficiency of 81 %.