The　deposition　process　of　passivation　layer　for　GaN-LEDs　can　affect　the　optical　and　electric　properties　of　these　devices.　In　this　paper,　we　use　an　ammonia-free　process　to　deposit　the　silicon　oxynitride　film　at　low　temperature　(100　degrees　C)　through　plasma　enhanced　chemical　vapor　deposition　(PECVD)　to　serve　as　the　passivation　layer　of　GaN-LEDs,　investigating　the　relationship　between　the　refractive　index　of　silicon　oxynitride　film　and　the　light　output　of　GaN-LEDs,　and　furthermore,　analyzing　the　properties　of　the　devices　before　and　after　the　passivation.　It　is　found　that　the　film　with　the　refractive　index　of　1.54　possesses　good　characteristics　and　the　optical　and　electrical　properties　of　GaN-LEDs　improve　greatly　after　the　deposition　of　the　layer.　Compared　with　the　optical　and　electrical　properties　of　GaN-LEDs　without　a　passivation　layer,　the　light　output　can　be　increased　by　as　high　as　17.8%　after　the　deposition　of　the　silicon　oxynitride　passivation　layer;　the　forward　voltage　decreased　and　the　reverse　leakage　current　reduced　obviously.　The　deposition　process　can　greatly　improve　the　optical　and　electric　characteristics　of　GaN-LEDs.　(c)　2006　Elsevier　Ltd.　All　rights　reserved.