Temperature and thermal characteristics of InGaN/GaN vertical light-emitting diodes on electroplated copper

We report the InGaN/GaN multiple quantum well vertical light-emitting diodes (VLEDs) operating at λ ~ 450 nm by the use of laser lift-off and copper electroplating processes. The thermal characteristics of fabricated VLEDs are measured and analyzed in terms of the junction temperature (Tj) using the forward voltage method, which allows us to estimate the thermal resistance (Rth). Between 298 and 378 K, the characteristic temperature is measured to be about 903 K at 350 mA. The far-field patterns of the VLED have a uniform and good near-Lambertian emission. The Tj and Rth values are also confirmed by the emission peak wavelength shift method. The use of electroplated copper with a high thermal conductivity instead of a sapphire substrate provides much better heat dissipation capability. For a 1 × 1 mm2 VLED, the low Tj value of 305.8 K is obtained with an output power of 191 mW at an injection current of 350 mA at 298 K, exhibiting Rth = 7.98 K W−1.

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