AlGaInP-Based LEDs With Al-doped ZnO Transparent Conductive Layer Grown by MOCVD

In this paper, Al-doped ZnO (AZO) grown by metal-organic chemical vapor deposition (MOCVD) using H
₂
O as an oxidizer was employed as a transparent conductive layer (TCL) in AlGaInP-based light emitting diodes (LEDs). A direct ohmic contact structure was observed between the AZO and the carbon-doped p
⁺
-GaP (p
⁺
-GaP:C) contact layer with a specific contact resistance of 2.2 × 10
^-4
cm
²
. It is attributed to the unintentional hydrogen-doped n
⁺⁺
-AZO interfacial layer at the clear interface of the AZO/p
⁺
-GaP:C. A forward voltage (V
_f
) of 1.99 V at 20 mA was achieved, which is lower than that of the ITO-TCL LED with a Vf of 2.07 V. In addition, compared with the conventional LED without TCL and the ITO-TCL LED, the studied LED demonstrates high output power and high wall-plug efficiencies. These results indicate that the AZO-TCL grown by MOCVD using H2O as an oxidizer is an effective current spreading layer for high-performance AlGaInP-based LED application.