Gallium Nitride-based high electron mobility transistors (GaN HEMTs) are at the cutting edge of technological innovation. Renowned for their high speed and power capabilities, GaN HEMTs are utilized across a diverse array of sectors, including telecommunications, power electronics, aerospace, defense, industrial, medical, and consumer electronics. Integrating GaN with an aluminum nitride (AlN) barrier enhances speed, power output, and thermal management. However, traditional HEMTs have reached the physical limits of their operational speed. This thesis investigates the addition of a ferroelectric hafnium zirconium oxide (HZO) layer beneath the gate of AlN/GaN HEMTs to overcome these limitations. This is achieved through the use of the remnant polarization of ferroelectrics to modulate the threshold voltage and demonstrate the ability for memory. Through the development of multiple HEMT devices with varying HZO thicknesses, hysteresis in device output currents is verified and alterable, exhibiting a threshold voltage tuning range of 0.5-1.2 V. The thesis also addresses the challenges and uncertainties associated with processing devices and working with ferroelectrics, emphasizing the necessity for meticulous care throughout the process. Overall, this work lays the foundation for the benefits of incorporating ferroelectric layers under the gate of AlN/GaN HEMTs, paving the way for faster devices in the future.