Modern　society　is　the　development　stage　of　informationization　and　intelligence,　and　display　is　the　key　factor　to　realize　information　exchange　and　intelligence.　Among　the　many　current　displays,　Micro　lightemitting　diode　(μLED)　display　is　used　as　a　disruptive　next-generation　display.　Based　on　the　same　GaN　material　and　process　platform,　we　propose　the　vertical　integrated　device,　where　Indium　Gallium　Nitride/Gallium　Nitride　(InGaN/GaN)　based　μLED　and　GaN　bipolar　junction　transistors　(BJT)　monolithically　integrated　vertically　on　a　single　GaN　chip.　The　ultraviolet　optoelectronic　characteristics　of　μLED　on　BJT　(LET)　devices　were　simulated　by　using　Silvaco　TCAD　software.　By　optimizing　the　size　and　concentration　of　the　epitaxy　layer,　the　optimized　integrated　device　is　obtained　with　high　current　gain　and　strong　response　to　UV　light.　The　LET　can　be　used　as　both　receiver　and　emitter,　which　is　regulated　by　changing　the　light　input　power　or　base　voltage.　This　device　can　be　driven　by　the　base　voltage　and　UV　light　alone,　which　is　a　multifunctional　integrated　device　for　light　emitting,　detecting,　sensing,　driving　and　regulating.　©　2024　John　Wiley　and　Sons　Inc.　All　rights　reserved.