Two important requirements for improving blue-green laser devices towards room temperature, cw operation are to decrease barrier resistance at the ZnSe-GaAs heterointerface for p-type materials, and, in general, reduce contact resistance in p-n junction devices. In both areas, application of newly developed interfacial engineering methods holds substantial promise. For ZnSe-GaAs heterojunctions, we have exploited molecular beam epitaxy growth kinetics to achieve different interface configurations and change the band alignment. Our results indicate a strong correlation between the Zn/Se beam pressure ratios employed during the early growth stage, the interface composition and the band offsets. Interface stability, however, also depends on interface composition. As far as ohmic contacts are concerned, the fabrication of suitable local interface dipoles at metal/II-VI interfaces should be explored as a new method to lower the Schottky barrier.