Farshid Kargosha, Z. Kordrostami, Investigation of HEMT and MESFET with Notch in Side of Drain, Journal of Engineering and Applied Sciences, Volume 11,Issue 4, 2016, Pages 742-746, ISSN 1816-949x, jeasci.2016.742.746, (https://makhillpublications.co/view-article.php?doi=jeasci.2016.742.746) Abstract: In this study, we investigate the requirement of high electron mobility field-effect transistors with hetero-structure and evaluate its performance at the high-frequency circuits. Needs, benefits and so computing the transistor are fully described. High electron mobility transistors are divided into three groups: pHEMT, mHEMT and induced HEMT. Quantum mechanism of electron in the channel and potential wells provides the most traits for high frequency transistors. Through drift-diffusion simulation shows that gate with small notch in side of the drain, can improve drain current and cutoff frequency. This indicates that without changing the gate length, capacitor of gate-source can be reduced. Keywords: Quantum Well FETs (QWFETs);High Electron Mobility Transistor (HEMT);quantum well;two Dimensional Electron Gas (2DEG);drift