C. J. Deatcher et al

Introduction Currently III−nitride semiconductors from the GaN family are demonstrating unparalleled performance in short−wavelength optoelectronic devices. Device performance improved rapidly during the 1990s [1,2], owing largely to advances in MOVPE growth of GaN itself, plus the ternary alloys InGaN and AlGaN. Effective doping of AlGaInN materials is critical for electrical−injection devices, and considerable challenges remain with p−doping using magnesium sources. Some of these issues are discussed in our accompanying presentation at this meeting. Meanwhile n−doping of GaN and related alloys has matured sufficiently to justify the exploration of novel dopant sources. Currently the sources of choice in MOVPE are the gaseous silicon hydrides monosilane [2] and disilane. These are used as dilute mixtures (typically 50−200 volume ppm) in hydrogen, posing hazards of flammability and toxicity, and requiring specialised gas−handling equipment. Also, since usage rates are low, there are concerns over long−term decomposition during cylinder storage. It is ultimately desirable to replace silicon hydrides with less hazardous, stable silicon sources, preferably in liquid form. For these reasons, we have explored the use of ditertiarybutylsilane (DTBSi) as a precursor for the growth of Si:GaN.