The present status of the research on alternative metalorganic P- as well as As-compounds is briefly summarized, leading to tertiarybutylphosphine (TBP) and tertiarybutylarsine (TBAs) as optimal choices as P- and As-precursors for III/V-epitaxy techniques. A variety of different N-compounds is applied for the MOVPE deposition of III-nitride layers. Due to the different thermal cracking behavior of alkylamine compounds as compared to the respective P- and As-counterparts, these compounds lead to a high C-incorporation. Thus, 1,1-dimethylhydrazine (UDMHy) or correspondingly substituted hydrazine compounds seem to be the most viable alternative sources for N in MOVPE. In addition, the realization of high-quality heterostructures in the novel, metastable (GaIn)(NAs)/GaAs material systems using TBAs and UDMHy is described leading to GaAs-based 1.3 mu m laser diodes with promising device characteristics. Finally, the realization of high purity, low-O-content (AlGa)As and (AlGaIn)P layers using TBAs and TBP, respectively, is demonstrated. These experiments clearly underline that the application of TBAs and TBP not only leads to a safer and more efficient epitaxial growth process but offers distinct advantages in particular for the realization of high-quality layers and novel device structures at reduced deposition temperatures also for high-Al-concentration heterostructures.