Experimental analysis and theoretical model for anomalously high ideality factors in ZnO/diamond p-n junction diode

High-quality heterojunctions between p-type diamond single-crystalline films and highly oriented n-type ZnO films were fabricated by depositing the p-type diamond single-crystal films on the Io-type diamond single crystal using a hot filament chemical vapor deposition, and later growing a highly oriented n-type ZnO film on the p-type diamond single-crystal film by magnetron sputtering. Interestingly, anomalously high ideality factors (n≫2.0) in the prepared ZnO/diamond p–n junction diode in the interim bias voltage range were measured. For this, detailed electronic characterizations of the fabricated p–n junction were conducted, and a theoretical model was proposed to clarify the much higher ideality factors of the special heterojunction diode.