Journal of Ovonic Research Vol. 19, No. 6, November - December 2023, p. 763 - 773 Colossal permittivity, impedance analysis and electric properties in AlGaN/GaN HEMTs H. Mosbahi a , A. Essaoudi b , N. E. Gorji c , A. Gassoumi d* , A. Almohammedi e, A. Helali f , M. Gassoumi b a Department of Transport Technology and Engineering, Higher Institute of Transport and Logistics, University of Sousse, Tunis b Laboratory of Condensed Matter and Nanosciences, University of Monastir, Monastir 5000, Tunisia c Mechatronic Engineering, Technological University Dublin, Dublin 15, Ireland d Department of Physics, Faculty of Science, King Khalid University, P.O. Box 9004, Abha, 61413, Saudi Arabia e Department of Physics, Faculty of Science, Islamic University of Madinah, Madinah, 42351, Saudi Arabia f Laboratory of Micro-Optoelectronics and Nanostructures (LMON), University of Monastir, Avenue of the Environment, 5019 Monastir, Tunisia The electric and dielectric processes of AlGaN/GaN/Si HEMTs produced by molecular beam epitaxy were examined utilizing direct current-voltage, impedance spectroscopy, and DLTS measurements. Using current-voltage measurements, the DC electrical characteristics of AlGaN/GaN/Si HEMTs revealed the self-heating effect. The relaxation dynamics of charge carriers appear to be studied by the conductance mechanism and electric modulus formalisms. Behavior that is frequency dependent has been observed in impedance spectroscopy. Last but not least, DLTS data have demonstrated the existence of electron traps. The prevalence of parasitic effects and conduction mechanisms are remarkably correlated with deep levels. (Received October 22, 2023; Accepted December 13, 2023) Keywords: AlGaN/GaN/Si HEMTs, DC measurements, Conductance, Impedance spectroscopy, Dielectric measurements, Electron trap, DLTS 1. Introduction AlGaN/GaN high electron mobility transistors (HEMTs) have drawn lots of attention for high-frequency and high-power applications [1-4]. Nitride based materials feature properties such as wide band gaps, large breakdown bias voltage, high saturation velocity, high electron mobility, high efficient carrier transport as well as a wurtzite material [5]. A two-dimensional electron gas (2DEG) in AlGaN/GaN heterointerface results from high carrier density due to the effect of strong spontaneous and piezoelectric polarization fields [6]. Silicon, sapphire and silicon carbide are the substrates on which the nitride layer are grown [7,8]. These substrates determines the crystalline quality of the layers and leads to high dislocation densities [9]. By optimizing the growth condition and design parameters, performance of AlGaN/GaN heterostructure transistors have been improved [6, 10-12]. Encouraging results were obtained in this research field. Reliability limitation of HEMTs AlGaN/GaN has primarily focused on impurities and defects. Know reliability issues for HEMTs AlGaN/GaN are parasitic effects due to current collapse, self-heating, kink effect, leakage current, gate-lag, drain-lag as well as traps in devices [13-17]. The origin of the parasitic effects were characterized by different techniques. The techniques are current-voltage measurements, capacitance-voltage characteristics, pulse measurements, deep level transient spectroscopy, Fourier transform deep-level transient spectroscopy, conductance deep level transient spectroscopy and impedance spectroscopy * Corresponding author: abdelaziz.gassoumi@gmail.com https://doi.org/10.15251/JOR.2023.196.763