Nitride-based light emitting diodes with Si-doped In/sub 0.23/Ga/sub 0.77/N/GaN short period superlattice tunneling contact layer

The electrical properties of Si-doped n/sup +/-In/sub 0.23/Ga/sub 0.77/N/GaN SPS structure were investigated and compared with conventional Mg-doped GaN contact layer. Temperature dependent Hall measurement showed that such a SPS structure exhibits a high sheet electron concentration. It was found that we could reduce the 20 mA LED forward voltage from 3.78 V to 2.94 V and also reduce the series resistance of the LED from 41 /spl Omega/ to 10 /spl Omega/ by introducing such an n/sup +/-InGaN/GaN SPS top contact. It was also found that we could improve the LED lifetime by such a SPS structure.