Selective zinc diffusion for GaAs/sub 0.6/P/sub 0.4/ LED arrays

The fabrication of linear red LED arrays in an undergraduate laboratory is described. Isolated p/sup +/-n junctions are formed by selective zinc diffusion into n-type GaAs/sub 0.6/P/sub 0.4/ wafers. The performance of several thin film diffusion mask materials is compared. The investigated mask materials include phosphosilicate glass, silicon nitride, and silicon. Enhanced lateral diffusion of zinc under the mask along the SiO/sub 2/-GaAs/sub 0.6/P/sub 0.4/ interface is observed for all of these mask materials. Phosphosilicate glass films provide the best results, however, even in this case, the lateral diffusion is nearly nine times the diffusion depth. Electrical and optical characteristics of the resulting LED arrays are presented.