Abstarct: Dilute Nitride Semiconductors (low nitrogen-containing ternary and quaternary alloys) have recently attracted much attention due to their fundamental properties promising for device applications in optoelectronics and photonics; such as highly efficient near infrared lasers, multi-junction solar cells, light emitting diodes(LED's) as well as heterojunction bipolar transistors (HBTs). Among these alloys, bulk and nanostructures of InGaNAs/GaAs and InGaNP/GaAs are suitable for optical telecommunication and multi-junction solar cells. Incorporation of a few percent of the nitrogen in these semiconductors causes modification of some typical features of their hosts, which for instance include:  Enhancement of maximum achievable free electron concentration in highly doped GaInNAs:Se as compared with GaAs:Se with the same dopant concentration.  Non-monotonic dependence of electron mobility on electron concentration of GaInNAs:Si after different annealing.  Transformation of optical features after incorporation of nitrogen in GaInP/GaAs structures and so on. For explanation of these phenomena we take advantage of: Band anti-crossing model, Amphoteric native defects model, Diffusion process of Si in alloys due to annealing, and Mutual passivation effects. Finally we found that after incorporation of nitrogen in GaInAs the enhancement of the available DOS leads to a much larger concentration of uncompensated, electrically active donors for the same dopant concentration According to the theory of Mutual passivation, Si donors and nitrogen atoms form stable SiGa-NAs nearest-neighbor pairs, due to annealing of dilute nitride alloys. Thus for investigation of dependence of electron mobility on electron concentration, we have to consider effects of SiGa-NAs pairs like as neutral scattering center. According to our analyses on experimental evidences of nitrogen on band structure of dilute nitrides, we are satisfied that incorporation of nitrogen in investigated samples transforms type I band alignment at the interface of free nitrogen GaInP/GaAs to type II band alignment in GaInNP/GaAs heterostructures.