ISSN 2394-3777 (Print) ISSN 2394-3785 (Online) Available online at www.ijartet.com International Journal of Advanced Research Trends in Engineering and Technology (IJARTET) Vol. 4, Issue 5, May 2017 All Rights Reserved © 2017 IJARTET 22 AlGaN/GaN HEMT on SiC-substrate Using AlN- spacer & Nucleation Layer For Improvement Over- Pinch-Off, Saturation & Breakdown Characteristics Rahul Ranjan 1 , Rajesh Kumar Mishra 2 , Rajkumar Mistri 3 Assistant Professor, Department of ECE, RTC Institute of Technology, Ranchi, India 1 Assistant Professor, Department of ECE, Centurion University of Technology & Management, Paralakhemundi, India 2 Assistant Professor, Department of ECE, RTC Institute of Technology, Ranchi, India 3 Abstract: This paper work focuses on the characteristic study of AlGaN/GaN HEMT, depending on some physical parameters of the material used. AlGaN/GaN HEMTs having feature of high saturation current, low pinch-off and hence lower on-resistance and higher switching speed, due to the high electron mobility at the hetero-junction. The high electron mobility is caused by two dimensional electron gas (2-DEG).Analysis suggests that the on-resistance of AlGaN HEMTs is lower than that of SiC FETs, depending on the mole fraction of Aluminum (i.e. Aluminum composition). Device simulation was done on Silvaco ATLAS to analyze into the operation mechanism on different types of GaN HEMTs and shows that the high breakdown voltage devices design is possible with AlGaN/GaN. Keywords: AlGaN/GaN HEMT, 2-DEG, Pinch-off, saturation, SiC-substrate and Silvaco ATLAS. I. INTRODUCTION In present work the different designs are presented and evaluated and the results based on substrate selection are reported. According to our choice of substrate selection, SiC reported better performance than Si. Furthermore in this thesis-work other advantages of individual and combined implementation of AlN nucleation layer and AlN spacer layer were studied separately. In this thesis-work for small signal analysis S-parameters smith chart curve also achieved which shows a close resemblance of maximum oscillation frequency and high cutoff frequency [1][2]. II. PROPOSED CONSTRUCTION DESIGN Fig.1: Schematic construction of proposed AlGaN/GaN HEMT Here a finally proposed simulated device with implementation of both spacer layer of 1nm and Nucleation layer of 30nm with Si substrate and SiC substrate separately with sidewall doping was studied and observation shows a clear improvement in saturation current from 24mA to 30mA and pinch-off voltage rises from -5V to -7v on SiC substrate compared to Si substrate [3], [4]. From these results we can say that, a decreased performance was observed with the use of Si substrate on the device as compared to SiC substrate. Moreover from the result analysis, we can say high saturation current and low pinch- off are the results due to– two dimensional electron gas (2-DEG). Fig.2: Energy band diagram showing 2-DEG. As the Fermi level must be continuous over the entire semiconductor heterostructure and due to this energy bands bends and a potential well or an energy valley forms at that heterostructure. In addition to this a potential profile and hence amount of charges induced at the interface in an AlGaN/GaN due