Progress in nitride semiconductors from GaN to InN-MOVPE growth and characteristics

This paper reviews the field of nitride semiconductors ranging from GaN to InN with respect to metalorganic vapor phase epitaxy growth and characteristics starting from the period of single-crystalline films. Progress has been made on many fronts. For InGaN, a key material for the emitting layer of blue light-emitting-diodes, using nitrogen as the carrier and bubbling gases for metalorganic sources has been found to enhance indium incorporation, and composition control of InGaN has been achieved. The phase separation of the InGaAlN system has been semiempirically predicted using the strictly regular solution model. Regarding InN, which is a mysterious material, its band-gap energy has been found to be half the reported value. The polarity of the substrate has been found to affect the characteristics of epitaxially grown GaN. Finally, from a future perspective, InGaAlN laser diodes promise a laser diode with uncooled and high power operation, which is strongly required for optical communications systems.