Vertical light-emitting diodes (VLEDs) with diamondlike carbon/titanium (DLC/Ti) heat-spreading layers on silicon (Si) substrates are investigated. Good thermal conductivity coupled with a thermal expansion coefficient similar to that of gallium nitride enables DLC/Ti to enhance heat dissipation via the Si substrate for Si-bonded VLEDs. The relative light intensity of VLEDs with DLC/Ti operating at 1 A is 10% greater than that of VLEDs without DLC/Ti. The output power droop can be further improved. A slight red shift of 0.5 nm occurs when the injection current is increased from 0.7 to 1 A. VLEDs with DLC/Ti also have lower and more uniform surface temperatures than VLEDs without DLC/Ti. The measured thermal resistance of VLEDs with and without DLC/Ti is 0.63 and 1.51 K/W at an injection current of 350 mA, respectively. This observation shows that the proposed DLC/Ti heat-spreading layer facilitates efficient thermal management in VLEDs.
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