Analytical Characterization of Unipolar Diode Based on Transistor Channels Model

In this paper, we propose an analytical approach for the small-signal response of nanometric InGaAs diode which is extracted to the transistor model in ref [1] when the gate is taking away. The exploitation of the small-signal equivalent circuit elements such as the admittance parameters can give significant information about the noise level of the devices by using the Nyquist relation. The analytical model takes into account the longitudinal and the transverse electric fields through a pseudo two-dimensional approximation of the Poisson equation. For the transistor, the total currents -potentials matrix relation between the gate and the drain terminals determine the frequency-dependent of the small-signal admittance response. The noise calculated by using the real part of the transistor/diode admittance under a small-signal perturbation. The results show that the admittance spectrum exhibits a series of resonant peaks corresponding to the excitation of plasma waves. The appearance of the resonance is discussed as functions of the device geometry (devices length) and the operating temperature. The model can be used, on one hand; to control the appearance of the plasma resonances, and on other hand; to determine the noise level of the InGaAs transistor and diode for the terahertz detection.