InGaN-GaN light emitting diodes grown by molecular beam epitaxy

Light emitting diodes consisting GaN homojunctions, InGaN-GaN double heterostructures (DH), and InGaN-GaN multiple quantum wells (MQW) were grown by molecular beam epitaxy (MBE). Using a plasma nitrogen source and solid sources for Ga, In and dopants, all structures contain an 1 μm n-GaN (doped with Si to mid 10 ¹⁸ cm ^-3 ) and 0.5 μm p-GaN (doped with Mg to low 10 ¹⁷ cm ^-3 ). In addition, the DH structures contain an active layer of InGaN with 13% In, and the MQW structures contain an active region of 10 periods of InGaN-GaN quantum wells. Blue electroluminescence is observed for both homojunction and DH structures, whereas white emission is observed for the MQW structures. The minimal injection current needed for emission is the lowest for MQW and highest for the homojunction structures. Possible phase separation of InGaN in the MQW structures is a suggested reason for the observed white emission.