EMISSION PROPERTIES OF INGAALP VISIBLE LIGHT-EMITTING-DIODES EMPLOYING A MULTI-QUANTUM-WELL ACTIVE LAYER

Visible InGaAlP light-emitting diodes (LEDs) employing a multiquantum- well (MQW) active layer have been investigated. Photo luminescence mea surements showed that growth on a GaAs substrate, with an intentional surface misorientation from the (100) plane towards the [011] directio n, 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%. Th e emission wavelength could be further reduced by 10 nm without any si gnificant decrease in the external quantum efficiency.