An improved model for current voltage characteristics of submicron SiC MESFETs Mohammad Riaz, Muhammad Mansoor Ahmed ⇑ , Usama Munir Department of Electrical Engineering, Capital University of Science and Technology (CUST), Islamabad, Pakistan article info Article history: Received 13 August 2015 Received in revised form 6 March 2016 Accepted 9 April 2016 Available online xxxx The review of this paper was arranged by Prof. S. Cristoloveanu Keywords: Submicron SiC MESFET Microwave devices High power MESFETs Swarm optimization Simulation and modeling abstract This paper presents an improved model to simulate I  V characteristics of submicron SiC MESFETs, designed for microwave power applications. The proposed model adequately addresses a non-ideal Schottky behavior, commonly observed in submicron devices, by adjusting the device biasing through simulation variables. Swarm optimization technique has been applied to investigate gate length (L g ) dependent performance of various SiC MESFETs models. It has been found that the proposed model provides an improved accuracy, ranging from 7% to 24%, compared to the best models available in the literature. This enhanced performance is primarily associated with the extra control, provided by the proposed model to simulate the movement of the depletion region in the channel as a function of applied voltages. An attempt has been made to identify the location underneath the Schottky barrier gate, where the depletion region gets its maximum height and thus controls the saturation current of the channel. Physical and electrical parameters of various SiC MESFETs having L g = 0.4 lm, 0.5 lm, 0.6 lm and 0.7 lm have also been assessed. An accurate assessment of the physical parameters of the device exhibits the validity of the model for submicron SiC MESFETs. Ó 2016 Elsevier Ltd. All rights reserved. 1. Introduction Silicon Carbide (SiC) MESFETs have shown a great potential in microwave power applications, mainly because of their material properties. Since their inception in the mid-eighties, these devices have improved significantly over a period of time [1]. Today SiC MESFETs offer high power density, high operating voltage and high operating temperature, compared to Si and GaAs based FETs. More- over, the operating frequency of SiC MESFETs has also improved, and submicron devices can comfortably work in X-band with CW power density as high as 7.8 W/mm [2]. The superior high power performance of SiC MESFETs is primar- ily associated with the properties offered by SiC which include: (a) wide band gap; (b) high electron saturation velocity; (c) high ther- mal conductivity and (d) high break down electric field. The high operating voltages, on the one hand, provided capability to SiC MESFETs to handle large power, but, on the other hand, it imposed stringent conditions on the device fabrication and physical geom- etry to realize its intended performance [3–7]. A simple way to improve the high frequency performance of a SiC MESFET is to reduce its gate length, L g , as this improves its unity gain frequency, f T as [8]: f T ¼ g m 2pC gs ð1Þ where g m is the extrinsic transconductance and C gs is gate to source capacitance. However, reduction in L g , especially to submicron dimensions, enhances the short channel effects namely: (a) shift in threshold voltage, V T ; (b) increase in output conductance, g d , in the saturation region of operation; (c) compression in g m and (d) an early self-regulating break down [9]. For S-band applications, Clark and Palmour fabricated L g ¼ 0:7 lm SiC MESFETs and their AC and power characteristics were investigated [10]. Gang et al. reported L g ¼ 0:6 lm SiC MESFETs and investigated their pulsed I  V response to determine the effects of self-heating on its DC characteristics [2]. Song et al. fabricated L g ¼ 0:5 lm SiC MESFETs and investigated effects of buffer layer thickness on the device breakdown [11]. Hjelmgren et al. fabricated and studied electro-thermal simulation of micro- wave SiC MESFETs having L g ¼ 0:4 lm. Their devices exhibited self-regulating break down much earlier than the channel pinch- off [12,13]. Assessment of I  V characteristics of a SiC MESFET is the first step to establish the quality of a device. An accurate assessment of the device I  V characteristics will enable a design engineer to use the device successfully in microwave power amplifiers [14,15]. There are two main techniques which can be employed http://dx.doi.org/10.1016/j.sse.2016.04.002 0038-1101/Ó 2016 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Solid-State Electronics xxx (2016) xxx–xxx Contents lists available at ScienceDirect Solid-State Electronics journal homepage: www.elsevier.com/locate/sse Please cite this article in press as: Riaz M et al. An improved model for current voltage characteristics of submicron SiC MESFETs. Solid State Electron (2016), http://dx.doi.org/10.1016/j.sse.2016.04.002