Unipolar transport and shot noise in metal–semiconductor–metal structures

Abstract

We carry out a self-consistent analytical theory of unipolar current and noise properties of metalsemiconductor-metal structures made of highly resistive semiconductors in the presence of an applied bias of arbitrary strength. By including the effects of the diffusion current we succeed in studying the whole range of carrier injection conditions going from low level injection, where the structure behaves as a linear resistor, to high level injection, where the structure behaves as a space charge limited diode. We show that these structures display shot noise at the highest voltages. Remarkably the crossover from Nyquist noise to shot noise exhibits a complicated behavior with increasing current where an initial square root dependence ͑double thermal noise͒ is followed by a cubic power law.

Shot Noise in Linear Macroscopic Resistors

“…Moreover, it displays linear velocityfield characteristics up to several kV=cm at room temperature [12], thus allowing one to apply considerable high voltages without the presence of hot-electron effects. Furthermore, the use of metal-semiconductor contacts is motivated by the fact that metals on semi-insulating materials exhibit the required nearly perfect Ohmic behavior in a wide range of voltages, since the carrier density at the interface imposed by the contact is of the same order of magnitude as the free carrier density of the semi-insulating material [13]. This fact avoids the presence of spurious space charge effects.…”

“…Furthermore, the use of metal-semiconductor contacts is motivated by the fact that metals on semi-insulating materials exhibit the required nearly perfect ohmic behaviour in a wide range of voltages, since the carrier density at the interface imposed by the contact is of the same order of magnitude as the free carrier density of the semi-insulating material. [13] This fact avoids the presence of spurious space charge effects. Taken, for example, at T =323 K, the device displays an almost symmetric linear current-voltage (I − V ) characteristics between 50 and + 50 V. The forward characteristics is shown in Fig.…”

Semi-classical noise investigation for sub-40nm metal-oxide-semiconductor field-effect transistors

“…This noise suppression has been discussed in many publications. 13,14 The aim of this paper is to provide further insight to the subject of shot noise in MOSFETs operating at high frequencies, and formulate a physical model to predict its effect on device performance by employing a semi-classical approach, thus keeping the calculations simple.…”

Analytical Physical Model for Electrolyte Gated Organic Field Effect Transistors in the Helmholtz Approximation

“…We observe only slight deviations for the more negative source-gate voltages V GS , which are due to the presence of access series resistance effects, as will be discussed below. The compact explicit I-V model based on Lambert's function (Equation (21) with Equation ( 27)) reproduces accurately the exact analytical model (red dashed lines in Figure 4), where only slight deviations at around the crossover voltage V c are observed. Therefore, this explicit model constitutes a physical compact model to describe the I-V characteristics of EGOFETs in the Helmholtz approximation, with no adjustable phenomenological parameters.…”

“…The source and drain electrodes are assumed to form ideal metal-semiconductor diffusive injecting contacts. [20,21] Therefore, the hole density p S takes a fixed value at their surfaces, which depends on the metal-semiconductor barrier height (see Appendix A):…”