Emission Properties of InGaAlP Visible Light-Emitting Diodes Employing a Multiquantum-Well Active Layer

Abstract
Visible InGaAlP light-emitting diodes (LEDs) employing a multiquantum-well (MQW) active layer have been investigated. Photo luminescence measurements showed that growth on a GaAs substrate, with an intentional surface misorientation from the (100) plane towards the [011] direction, resulted in a marked improvement in the quality of the MQW compared with growth on a just (100) substrate. The emission properties of the LED strongly depended on the various parameters of the MQW structure, in particular the number of wells. The external quantum efficiency of a 600 nm LED with a 20-well MQW active layer was found to be 1.6%. The emission wavelength could be further reduced by 10 nm without any significant decrease in the external quantum efficiency.