A study of the surface of thermally diffused p(+)n indium phosphide structures for the fabrication of high efficiency radiation-resistant space solar cells

The surface of the p{dollar}sp+{dollar}n (Cd,S) Indium Phosphide (InP) thermally diffused homojunction solar cell was studied in order to reduce the effect of both the high surface recombination and the high surface reflection on the performance of the solar cell.; A thorough investigation was done on the optical, thermal and electrical characteristics of p{dollar}sp+{dollar}n InP solar cell surfaces passivated with an oxide chemically grown in an HNO{dollar}sb3{dollar}-based solution. This oxide is double layered with a phosphorus(P)-rich In(PO{dollar}sb3)sb3{dollar} oxide layer at the interface with the emitter surface and an outer Indium (In)-rich (In{dollar}rm sb2Osb3){dollar} oxide layer. The P-rich In(PO{dollar}sb3)sb3{dollar} interfacial oxide layer has an excellent passivating property, and was found to be very stable with respect to factors such as heat, humidity, prolonged exposure to light and ionizing radiation such as high energy electrons and protons. It has an average refractive index of 1.496 over the sunlight spectrum. We designed three-layer antireflective coatings (ARC) {dollar}rm (In(POsb3)sb3(100A)/Sisb3Nsb4(444A)/MgFsb2(792A){dollar} and {dollar}rm (In(POsb3)sb3(100A)/ZnS(413A)/MgFsb2(918A),{dollar} optimized for minimum current loss, with In(PO{dollar}sb3)sb3{dollar} as the first layer, to reduce the surface reflectance to less than 4%.; The combined benefit of this three-layer ARC with experimentally feasible improvements on the cell such as highly doped thinner emitter and low resistance low surface coverage (less than 5%) electroplated Au-Zn (Zn content {dollar}<{dollar}1%) contacts, should make our p{dollar}sp+{dollar}n (Cd,S) InP solar cell reach an efficiency over 20% with a V{dollar}rm sb{lcub}OC{rcub}{dollar} of more than 900 mV.