A study of GaN-Based Lateral Diode with Nanocrystalline Diamond Passivation Layer

Thermal accumulation under high output power density is one of the key bottlenecks faced by GaN-based power devices. The nanocrystalline diamond (NCD) passivation layer strategy plays a while the existing studies are focus on GaN-based HEMT. In this study, nanocrystalline diamond films with a thickness of 380-450nm were grown on Si-based AlGaN/GaN heterostructure materials using a microwave plasma chemical vapor deposition (MPCVD) system. Consequently, lateral Schottky barrier diode devices with NCD passivation were fabricated, and their electrical and thermal properties were investigated. The results show that the DC forward characteristics of the NCD-passivated diodes are essentially the same as those of devices without NCD passivation. Moreover, dynamic voltage tests reveal that the NCD passivation layer significantly mitigates current collapse in GaN devices at high frequencies. Under a -20 V DC bias and a pulse voltage of 2.5 V, the current density degradation is only 2.6%, whereas conventional devices almost completely degrade. Thermal imaging microscopy under varying DC power levels shows that thermal failure occurs at an output power density of approximately 4 W/mm for conventional devices, while NCD-passivated devices can reach around 7.5 W/mm. We also test the electrical degradation behaviour of NCD passivated device under long-time reverse bias. This work firstly demonstrates applying nanocrystalline diamond passivation to thermal management in GaN-based power diodes, clearly shows the potential of this strategy for non-HEMT power device applications. crucial role in improving heat dissipation in high-power GaN devices, while the existing studies are focus on GaN-based HEMT. In this study, nanocrystalline diamond films with a thickness of 380-450nm were grown on Si-based AlGaN/GaN heterostructure materials using a microwave plasma chemical vapor deposition (MPCVD) system. Consequently, lateral Schottky barrier diode devices with NCD passivation were fabricated, and their electrical and thermal properties were investigated. The results show that the DC forward characteristics of the NCD-passivated diodes are essentially the same as those of devices without NCD passivation. Moreover, dynamic voltage tests reveal that the NCD passivation layer significantly mitigates current collapse in GaN devices at high frequencies. Under a -20 V DC bias and a pulse voltage of 2.5 V, the current density degradation is only 2.6%, whereas conventional devices almost completely degrade. Thermal imaging microscopy under varying DC power levels shows that thermal failure occurs at an output power density of approximately 4 W/mm for conventional devices, while NCD-passivated devices can reach around 7.5 W/mm. We also test the electrical degradation behaviour of NCD passivated device under long-time reverse bias. This work firstly demonstrates applying nanocrystalline diamond passivation to thermal management in GaN-based power diodes, clearly shows the potential of this strategy for non-HEMT power device applications.