Studies on the characteristics of GaN-based Gunn diode for THz signal generation

A new technique has been developed to explore the potentiality of the newly emerging GaN material for use as Gunn diode and to study the device characteristics of the device. The results obtained for GaN diode are compared with those for GaAs-based Gunn diode. It is observed that GaN-based Gunn diode can generate two orders of magnitude more power than GaAs-based Gunn diode at similar operating conditions. The reported improvement in the mm-wave/THz-wave performance are supported by the high value of GaN Pf²Z figure of merit, which is 50-100 times higher than that for GaAs, indicating a strong potential of GaN for mm-wave signal generation. A detail study and suggestions are provided to the fabricators to fabricate GaN-based Gunn diode of different structures (like general profile, notch, forward and backward injection of the charge carriers, heterostructure etc). A novel method has also described to obtain the first hand data on thermal analysis. An output power of 1400 kW/cm² from the GaN Gunn diode as compared to the same of 4.9 kW/cm² from GaAs diode is note worthy.