n-ZnSe/p-GaAs heterojunction solar cells

For PV applications epitaxial layers of n-ZnSe were grown by metal-organic vapour phase epitaxy (MOVPE) at 340 degrees C on GaAs(001) substrates. n-type net carrier concentration in the range between 10(17)-10(19) cm(-3) was demonstrated. By increasing the doping concentration the double crystal x-ray diffraction full width at half maximum of 1.2 mu m thick ZnSe-layers increased from 400 " to 600 ". A first n-ZnSe/p-GaAs solar cell achieved an open circuit voltage of 706 mV, a fill factor of 65% and a short circuit current density of 10mAcm(-2) (total area, ELH-lamp, 100mWcm(-2), no AR-coating). J(sc) was increased by 4mAcm(-2) by depositing sputtered n(+)-ZnO on the n-ZnSe layer. In order to further improve the PV performance n-ZnSe will be grown on GaAs buffer layers, the doping profile will be optimised systematically and MgF2 will be deposited on the ZnO layer.