InGaN based light emitting diodes with Ga doped ZnO as transparent conducting oxide

We report on the electrical and optical properties of InGaN based light emitting diodes (LEDs) utilizing Ga doped ZnO (GZO) grown by molecular beam epitaxy (MBE) as a highly transparent contact p-electrode (GZO-LEDs). For comparison, the LEDs with semi-transparent thin Ni/Au (5/5 nm) current spreading layers were also fabricated on the same wafer (Ni/Au-LEDs). Unpackaged GZO-LEDs with 200 mu m diameter showed negligible light output degradation for up to 30 min under CW current of 100 mA (corresponding to a 318 A/cm(2) current density), while the light output for Ni/Au-LEDs was reduced by 85% after only 5 min of operation due to the severe current crowding effect (or current filamentation). Pulsed electroluminescence (EL) measurements revealed that the GZO-LEDs exhibit 50% higher EL intensity for the same current levels. (c) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim