High-performance　violet　light-emitting　diodes　(LEDs)　with　InGaN/AlInGaN　multiple　quantum　well　(MQW)　active　regions　were　grown　by　metal　organic　chemical　vapor　deposition　(MOCVD).　The　interface　flatness　of　the　InGaN/AlInGaN　MQWs　and　the　emission　efficiency　of　the　LED　are　firstly　improved　with　increasing　Al　content　in　the　AlInGaN　barrier　layer,　and　then　degraded　as　Al　content　increases　further,　being　optimal　when　Al　content　is　0.12.　Similarly,　the　result　is　optimized　if　the　indium　content　is　approximately　2.5%　in　the　AlInGaN　barrier　layer.　The　mechanisms　which　have　influences　on　the　radiative　efficiency　when　the　Al　content　increases　are　discussed.　A　high　output　power　of　7.3　mW　for　the　violet　LED　at　20　mA　current　has　been　achieved.　(c)　2006　Elsevier　B.V.　All　rights　reserved.