Improvement of diodes performance with a multiple-pair buffer layer by MOCVD

The GaN homo-junction light-emitting diodes (LEDs) with a multiple-pair buffer layer (MBL) were grown by metalorganic vapor phase epitaxy on sapphire substrates. Each pair of the buffer layer consists of a 300 Å thick GaN nucleation layer grown at a low temperature of 525°C and a 4 m thick GaN epitaxial layer grown at a high temperature of 1025°C. It is found that the GaN LEDs with a three-pair buffer layer will exhibit a low turn-on voltage, stronger electroluminescence intensity and higher light-output power as compared to the conventional growth without a buffer layer. This is attributed to the effective reduction in the propagation of defects and dislocations near the p–n junction for the LEDs with MBL.