Abstract—In this paper, we propose an analytical drain- current model for long-channel junctionless (JL) cylindrical surrounding-gate MOSFET (SRG MOSFET). It is based on surface-potential solutions obtained from Poisson’s equation using some approximations and separate conditions. Furthermore, analytical compact expressions of the drain-current have been derived for deep depletion, partial depletion, and accumulation mode. The confrontation of the model with TCAD simulation results, performed with Silvaco Software, proves the validity and the accuracy of the developed model. Keywords—Cylindrical surrounding-gate (SRG) MOSFET, junctionless (JL), analytical drain-current model, surface-potential. I. INTRODUCTION he junctionless transistors (JLTs) have attracted increasing attention from the scientific community and even the microelectronics industry since the development of these devices [1, 2]. The JLTs are depletion-mode devices with a highly doped channel and without junctions through the realization of one single type of doping concentration. Also, this type of transistors presents a near ideal subthreshold slope (~60mV/Dec), low leakage currents and less degradation of the mobility compared with the inversion mode transistors [3]. On the other hand, the cylindrical surrounding-gate MOSFET (SRG MOSFET) remains the best multiple-gate MOSFET transistor in terms of short channel effects (SCEs) control [4]. In addition, the junctionless (JL) SRG MOSFET transistor exhibits good electrical properties and excellent performances for future nanoscale CMOS circuits [5]. The electrostatic surface potential is an important parameter for describing DC property of junctionless devices. This key parameter is obtained from solving Poisson’s equation using adequate boundary conditions. However, the difficulty of solving Poisson’s equation in the cylindrical coordinates limits the development of analytical compact models for junctionless (JL) SRG MOSFET. Therefore, most of the developed analytical models for long-channel JL SRG MOSFET are “charge-based models” and a few of them are “surface- potential based models” [6, 7]. The theory of JL Nanowire devices is well described in [8], however the using of the Bessel functions complicated the analytical formulation of the derived solutions. In [9], the current-model for JL Nanowire is continuous but there are no analytical expressions for the drain-current and it is based on direct integral operations. In [10], the quantum mechanical effect is well incorporated in the model but it is valid just for depletion regimes. In this paper, we propose an analytical drain-current model for long-channel JL SRG MOSFET valid in all operating regions. It is based on the calculation of surface-potential obtained from relationships between surface potential and gate-voltage, which are derived from Poisson’s equation using a regional Analytical Drain-Current Model and Surface- Potential Calculation for Junctionless Cylindrical Surrounding-Gate MOSFETs Billel Smaani 1,2 , Samir Labiod 2,3 , Fares Nafa 4 , Mohamed Salah Benlatreche 5 , Saida Latreche 2 1 Ingénierie des Systémes Electriques Department, Faculty of Technology, Boumerdes University, Algeria 2 Laboratoire Hyperfréquences et Semiconducteurs, Electronique Department, Constantine 1 University, Algeria 3 Physique Department, Faculty of Sciences, Skikda University, Algeria 4 Boumerdes university, Faculté de Technologie, Laboratoire d’Ingénierie des Sytémes et des Telecommunication, Boumerdes, Algeria 5 Centre Universitaire Abdel Hafid Boussouf Mila, Algeria *Corresponding author is Billel Smaani: b.smaani@univ-boumerdes.dz Received: April 12, 2021. Revised: September 18, 2021. Accepted: September 8, 2021. Published: September 10, 2021. T INTERNATIONAL JOURNAL OF CIRCUITS, SYSTEMS AND SIGNAL PROCESSING DOI: 10.46300/9106.2021.15.149 Volume 15, 2021 E-ISSN: 1998-4464 1394