An LED (light emitting diode) array of the present invention has a plurality of light emitting diodes aligned in row on a substrate crystal. Each of the light emitting diodes has a double hetero-structure formed by causing a light emitting layer to be interposed between p-type and n-type semi-conductive layers and is isolated with isolating mesa grooves. A reflecting layer is provided between the substrate crystal and one of the p-type and n-type semi-conductive layers. The reflecting layer comprises a plurality of semi-conductive layers having at least different refractive indexes of 2 or more than 2-kinds, each of the semi-conductive layers made of semiconductor having the same polarity as that of the substrate crystal and having a wider forbidden band width than that of the light emitting layer. Further, the isolating mesa grooves are provided by a wet etching using an etching liquid of H.sub.3 PO.sub.4 .multidot.H.sub.2 O.sub.2 having volume ratio of H.sub.3 PO.sub.4 : H.sub.2 O.sub.2 =1.about.5:1, thus, the LED array having a high integration and a high light emitting output can be successfully produced.