One　of　the　bottlenecks　for　today＇s　micro-light-emitting-diodes　(micro-LEDs)　is　the　low　light　extraction　efficiency.　How　to　effectively　boost　this　efficiency　is　especially　important　for　micro-LEDs　because　their　surface-to-volume　ratio　is　much　larger　than　normal　LEDs.　The　trapezoidal　chip　structure,　surface　grating,　and　surface　coarsening　are　simulated　in　this　paper,　with　the　aim　to　obtain　their　contributions　to　enhance　the　light　extraction　efficiency.　Through　the　simulation,　we　have　found　that　all　of　the　three　methods　can　increase　the　light　extraction,　but　with　different　extents.　When　the　trapezoidal　angle　of　the　mesa　is　12°,　the　extraction　efficiency　reaches　its　maximum　(by　this　method)　of　64.5%.　If　the　surface　grating　on　n-GaN　(the　light　output　surface)　has　a　period　of　300　nm,　a　height　of　147　nm　and　width　of　243　nm,　the　light　extraction　efficiency　can　be　as　high　as　72%,　which　is　much　higher　than　that　of　the　micro-LED　without　any　grating.　For　the　random　roughening　of　n-GaN,　a　maximum　value　of　56%　can　be　obtained　if　the　roughness　extent　is　optimized.　Our　results　are　of　reference　value　for　scientists　and　engineers　working　in　micro-LEDs　and　can　serve　as　guidelines　for　GaN　based　high　efficiency　micro-LED　design　for　future　displays.　©　2022　Elsevier　B.V.