Improved Electrical Transport and Electroluminescence Properties of p‑ZnO/n-Si Heterojunction via Introduction of Patterned SiO₂ Intermediate Layer

The authors report on the fabrication and temperature-dependent current–voltage and electroluminescence properties of p-ZnO:As/n-Si heterojunction diodes. The As-doped p-ZnO material was prepared by out-diffusion of arsenic atoms from a sandwiched GaAs interlayer on patterned SiO₂/Si substrates. The introduction of hollow-shaped SiO₂ patterned layer promotes the efficiency of carrier injection into the active layer and considerably lowers the emission onset of the studied diode. The current–voltage characteristics of the heterojunction were detailedly studied in the temperature range of 21–120 °C to determine the dominant carrier transport mechanisms in different bias regions. The reverse saturation current, barrier height, and ideality factor were estimated from the thermionic emission model and found to be highly temperature dependent. An improved electroluminescence performance of the studied diode featuring an ultralow emission onset and an acceptable operation stability shows the potential of our approach. Long-term stability of the diode without encapsulation in air-exposure environment was also investigated by monitoring the electroluminescence evolution with storage time, and the oxygen-related surface adsorption was identified as the main cause for the undesirable emission decay.