diffused mesa transistor [dǝ¦fyüzd ¦mā·sǝ tran`zis·tǝr] ELECTRONICS A diffused-junction transistor in which an n-type impurity is diffused into one side of a p- type wafer; a second pn junction, required for the emitter, is produced by alloying or diffusing a p-type impurity into the newly formed n-type surface; after contacts have been applied, undesired diffused areas are etched away to create a flat-topped peak called a mesa. |