Selective growth conditions of ZnSe/ZnS heterostructures on (001) GaAs with metalorganic molecular beam epitaxy

Selective growth of ZnSe and ZnS on (001) GaAs substrates partially covered with SiOx was examined by metalorganic molecular-beam epitaxy. The growth temperature was the key factor for the selective growth, and the minimum growth temperature of ZnS to achieve selective growth was 450 degrees C. On the other hand, the minimum growth temperature of ZnSe was 500 degrees C. This difference of temperature for the selective growth made it difficult to grow high-quality ZnSe/ZnS heterostructures. To overcome this problem, we used periodic supply epitaxy to lower the selective growth temperature of ZnSe. Supply interruption after short time supply of ZnSe enhances the desorption of precursors especially on SiOx surfaces and this suppresses the nucleation of ZnSe on SiOx surfaces. The lower VI/II ratio also suppresses nucleation of ZnSe on SiOx. The selective growth of ZnSe was thus achieved at 430 degrees C with a VI/II ratio of 1. The minimum selective growth temperature reported on ZnSe up to now is 600 degrees C, and this work demonstrated the selective growth of ZnSe at a considerably lower temperature. We have prepared a ZnSe/ZnS single quantum well (SQW) at 450 degrees C under the selective growth condition and the bright band edge emission from the ZnSe well was observed by photoluminescence measurement at 13 K.