Reliable GaN-based THz gunn diodes with side-contact and field-plate technologies

Abstract

For the first time, Gallium Nitride(GaN)-based Gunn diodes with side-contact and field-plate technologies were fabricated and measured with reliable characteristics. A high negative differential resistance (NDR) region was characterised for the GaN Gunn effect using side-contact technology. The I-V measurement of the THz diode showed the ohmic and the Gunn effect region with high forward current of 0.65A and high current drop of approximately 100mA for a small ring diode width w of 1.5 μm with 600 nm effective diode height h at a small threshold voltage of 8.5V. This THz diode worked stable due to good passivation as protection from electro-migration and ionisation between the electrodes as well as a better heat sink to the GaN substrate and large side-contacts. The diodes can provide for this thickness a fundamental frequency in the range of 0.3 - 0.4 THz with reliable characteristics.