ABSTRACT

GaN and related materials such as AlGaInN are III-V nitride compound semiconductors with the wurtzite crystal structure and an energy band structure that allow direct interband transitions which are suitable for light-emitting devices (LEDs). GaN films are usually grown on a sapphire substrate with (0001) orientation (c face) at temperatures around 1000°C by the metal-organic chemical vapor deposition (MOCVD) method. Remarkable progress has been achieved in the crystal quality of GaN films by employing a new growth method using buffer layers. The ternary III-V semiconductor compound, GaInN, is one of the candidates for blue to blue-green emitting LEDs, because its bandgap varies from 1.95 to 3.4 eV depending on the indium mole fraction. It was very difficult to grow high-quality single crystal GaInN films due to the high dissociation pressure of GaInN at the growth temperature. High-brightness blue and blue-green GaInN/AlGaN DH LEDs with a luminous intensity of 2 cd have been fabricated and are now commercially available.