Characterization of n-doped branches in nanotree LEDs†

Abstract

We present processed light emitting diodes (LED) devices based on GaInP core-branch nanowire (NW) structures. The LEDs rely on the charge carrier diffusion induced light emitting diode concept. The GaInP core has a higher Ga content than the branches to induce diffusion of carriers from the cores into the branches. The branches play the role of the active region in the structure, where charge carriers recombine to emit light. We investigate the impact of n-doping the branches on the performance of the LEDs. Electroluminescence measurements provide insights on the emission spectrum with varying dopant molar fraction. External quantum efficiency (EQE) measurements provide insights into the device quality, and reveal the limitations encountered in processing, such as the high sheet resistance of the indium tin oxide (ITO) transparent conductive top contact. Temperature dependent measurements allow us to probe the effect of contact resistance by measuring the I–V curve as a function of temperature. The work identifies performance limitations and paths to overcome them.