MODEL PARAMETER EXTRACTION OF AlGaN/GaN HEMT AT MICROWAVE FREQUENCY

Abstract

Development of microwave power devices plays a crucial role in modern communicating world. From the point contact diode to the modern HBT’s and HEMT’s are the fascinating example of this marathon technological achievement. As said that “necessity is the mother of invention”, in science community is was well known that as time will pass we will have to develop more precise and more fast technology to fulfil the need of corresponding world demand, Resulting the HBT’s and HEMT’s comes into existence. Although the journey of getting these super fast devices was not so easy and it take 4 to 5 decade to become the reality. Discussion of this dissertation is based on latest technology called HEMT device. The main objective of this dissertation to take the suitable model for HEMT which suites the device performance up to 10 GHz. Then extract all parameter which belongs to the model and simulate these result and compare to the measured one. Small signal model and large signal model parameter extraction also carried out up to some limit and it is shown that good agreement between simulated result and measured data. In chapter 1 deal with introduction of what is high speed devices where it can be used and what is the objective of this dissertation work. Chapter 2 discussed the whole classical development of FET devices. Introducing the little bit idea of fabrication process of substrate of devices. Then the discussion about journey of high speed devices from the Si technology to the HEMT technology is carried out. What are those parameters which affect the device speed is also discussed in this chapter. Chapter 3 deals with AlGaN/GaN HEMT exclusively. This chapter deals with the formation of hetero – junction with two different band gap materials which finally lead to the development of HEMT. Then the comparison between different semiconductor materials, are use in making of FET’s. Substrate plays important role in FET’s so this chapter also discuss the material which is most suitable to the AlGaN/GaN HEMT and why. What are the advantages to take the GaN as a material is also cover at the end of the chapter 3. Chapter 4 cover the basic idea of modelling and data measurement. This chapter it is also mention what are those challenges which encountered at the time of modelling. S-Parameter measurement and De-embedding of measured data also give us some useful steps which are necessary for the modelling of HEMT devices. Chapter 5 come up with small signal modelling insight. The model which is used in this work (As the device which is used in this work having transit frequency 7-8 GHz) is suitable for parameter extraction. Then generate the mathematical equation by putting some legal approximation who does not affect the model performance. Simulated and measured data comparison given at the end of this chapter, which tells us that parameter extraction is quite good enough. Chapter 6 deal with large signal model parameter extraction, in particular the angelov model is taken to extraction procedure because in ADS and in IC-CAP use this model. Finally DC-IV parameter extraction and transfer characteristics parameter is extracted in IC-CAP and result is simulated in ADS to compare measured curve with simulated curve. Only 4.6% error comes in to the simulated curve with respect to measured one which is good agreement. Finally in the 6th chapter future scope and discussion carried out. Overall, successfully parameter extraction done and good agreement between simulated and measured data come.