Abstract
Indium tin oxide (ITO) ohmic electrode was employed to enhance the optical power in tunnel junction light emitting diodes (TJ-LEDs). The electrical and optical measurement showed that the lateral current spreading and brightness were considerably improved as compared to those of conventional p/n-junction LEDs, leading to the reduction of the forward voltage by means of 0.1 V. The TJ structure of LEDs consists of n+-InGaN/InGaN superlattice/n+-GaN/p-GaN grown a InGaN/InGaN single quantum well (SQW) on AlInN/GaN multi-buffer. The transmittance of ITO is 90–94% on 460–520 nm spectral ranges, and the total output power of SQW LEDs is effectively increased. The forward voltage of the SQW LEDs, including the voltage drop across the reverse-biased TJ is 3.2 V at 20 mA, while that of standard SQW LEDs with a conventional contact structure is 3.1 V at 20 mA. Furthermore, the output power of LEDs with the TJ is over 6 mW at 20 mA, while that of conventional LEDs is about 4.5 mW at 20 mA. Especially, the electrostatic discharge (ESD) value of fabricated TJ-LED chips is –5 KV at human body conditions. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Published Version
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