Jean-Michel Sallese

Gallium nitride (GaN) high-electron-mobility transistor (HEMT) biosensors have recently emerged as promising platforms for highly sensitive and label-free detection of biomolecules. Their exceptional electrical properties, including high carrier mobility, together with the wide bandgap and strong chemical bonds of GaN materials, provide excellent stability under high temperatures, ionizing radiation, and chemically harsh environments. Despite significant experimental progress, comprehensive analytical models capable of linking biomolecular recognition events to the electrical response of GaN biosensors remain limited. This work presents a physics-based, design-oriented analytical modeling framework for AlGaN/GaN HEMT biosensors. The model incorporates biomolecular binding kinetics, the dielectric properties of the hybrid system, and electrostatic coupling to the transistor channel conductivity. Numerical simulations are performed using COMSOL Multiphysics to validate the analytical model. The developed framework provides physical insight into the mechanisms governing biosensor operation and offers practical guidelines for the optimization and comparative assessment of HEMT/MIS-HEMT biosensor architectures.

This article presents an analytical model of the barrier layer in GaN-MISHEMT that predicts a limitation of the channel charge density that is expected to reach an asymptotic value under high gate voltages, a feature that was not reported before. We find that this behavior is very sensitive to the device parameters such as the AlGaN barrier thickness, composition, and polarization-induced charge density. Explicit relationships for charge saturation in the quantum well (QW) are proposed and can be used to optimize GaN-MISHEMT architectures.

Nanowire field-effect transistor (NW FET) biosensors are known to be highly sensitive devices that can detect extremely low concentrations of biomolecules. In this article, we present an analytical model alongside with numerical simulations to calculate the sensitivity of NW FET biosensors. The model accounts for biosensing dynamics as well as diffusion of ions in the solution and across the functionalized layer. The signal-to-noise ratio (SNR) is also estimated, which gives a lower limit in terms of sensitivity. The model is physics-based and is validated against COMSOL multiphysics simulations and experimental data. It predicts the biosensitivity down to the femtomolar concentration of biomolecules without any fitting parameter.

In this paper an analytical non-quasi-static (NQS) model for long-channel symmetric double-gate junctionless field-effect transistors (JLFETs) operating in depletion mode is proposed for the first time. The model addresses the limitations of existing DC and AC models by incorporating time-dependent current continuity equations which are essentials to predict JLFETs behavior at high frequencies. Leveraging charge-based equations, the NQS model captures the delay between current and applied potentials arising beyond the quasi-static regime. Analytical solutions for small-signal perturbations allow the calculation of key transistor small signal parameters such as the gate transadmittance. The model’s validity is tested against TCAD simulations for various device parameters, including doping concentration and channel thickness. Good agreement between the model and TCAD simulations is observed across a wide frequency range, up to highly non-static transport conditions. This work lays the foundation for a comprehensive RF model of JLFETs for high-frequency applications.

Electrostatically confined quantum dots in semiconductors hold the promise to achieve high scalability and reliability levels for practical implementation of solid-state qubits where the electrochemical potentials of each quantum dot can be independently controlled by the gate voltages.In this paper, the current and charge stability diagram of two-well potentials arising from electrostatically defined double quantum dot (DQD) are analytically realized. We propose to apply the Generalized Hubbard model to find the Hamiltonian of the system. The proposed analysis takes the tunnel coupling between the dots, Coulomb interaction, and Zeeman energy arising from an external magnetic field into account. Using quantum master equations to predict the probability of the final states in a DQD system, we study the tunneling current through two quantum dots coupled in series with two conducting leads, and therefore, the charge stability diagram is theoretically investigated. The impact of the tunnel coupling and Zeeman energy on the charge stability diagram is deeply discussed. The validity of the presented analysis is confirmed by experimental data as well as the classical capacitance model.

Predicting the performance of solar cells though analytical models is important for the theory-guided optimization of these devices. Earlier models neglect the impact of the optical generation in the quasi-neutral regions of a perovskite solar cell. Here, a new model is developed that takes optical generation in these regions into account. The model includes the full depletion approximation and the drift-diffusion transport mechanisms. A comparison with earlier models demonstrates the improved predictive power of the developed model. In addition, the accuracy of the model was assessed by comparing it prediction to experimental data obtained from working devices.

Relying on the previously developed charge-based approaches, this paper presents a physics-based design space of negative capacitance in double-gate and bulk MOSFET architectures. The impact of thickness variation of the ferroelectric on the DC characteristics has been deeply investigated. The model precisely estimates a critical thickness of ferroelectric at instability conditions before the device goes into the hysteresis regime. Explicit relationships have been driven for hysteresis voltages which can be used as a general guideline for technology optimization of negative capacitance FETs.

This article analyzes the design space stability of negative capacitance double-gate junctionless field-effect transistors (NCDG JLFETs). Using analytical expressions derived from a charge-based model, we predict instability condition, hysteresis voltage, and critical thickness of the ferroelectric layers giving rise to the negative capacitance behavior. The impact of the technological parameters is investigated in order to ensure the hysteresis-free operation. Finally, the stability of NCDG JLFET is predicted over a wide range of temperatures from 77 to 400 K. This approach has been assessed with numerical TCAD simulations.