The need of performance enhancement at the RF and millimeter wave is highly desirable to eliminate the heating effects and power dissipation. Silicon substarte found to be a suitable candidate which reduces about 70% channel temperature than sapphire. To achieve high performance, a GaN on the Silicon substrate high electron mobility transistor is designed and its various performance paramters are analyzed by varying the design specifications. Moreover, the problem of blocking voltage improvement is resolved by epitaxial design approach. Since, threshold voltage, doping-level, work-function of gate material and channel length are considered as some of the important parameters while device modeling. Therefore, the impact of these parameters is examined and analyzed to enehace the performance and reliability of the device for RF applications. The performance parameters like trans-conductance, drain current curves are plotted at different state of device physical and electrical parameters. Results exhibits maximum value of transconductance gm=13 milli-mho, minimum gate capacitance Cg=0.5pf, wheras Vth is varied between − 0.25 volts to 0.25 volts.