Heitler-London model for acceptor-acceptor interactions in doped semiconductors

The goal of the paper is to overview contemporary theoretical and experimental research of the microwave electric noise and fluctuations of hot carriers in semiconductors, revealing sensitivity of the noise spectra to non-linearity in the applied electric field strength and, especially, in the carrier density. During the last years, investigation of electronic noise and electron diffusion phenomena in doped semiconductors was in a rapid progress. By combining analytic and Monte Carlo methods as well as the available experimental results on noise, it became possible to obtain the electron diffusion coefficients in the range of electric fields where inter-electron collisions are important and Price’s relation is not necessarily valid. Correspondingly, a special attention to the role of inter-electron collisions and of the non-linearity in the carrier density while shaping electric noise and diffusion phenomena in the non-equilibrium states will be paid. The basic and up-to-date information will be presented on methods and advances in this contemporary field - the field in which methods of non-linear analytic and computational analysis are indispensable while seeking coherent understanding and interpretation of experimental results.

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Nanoscale Capacitance and Capacitance-Voltage Curves for Advanced Characterization of Electrical Properties of Si and GaN Structures Using Scanning Microwave Impedance Microscopy

ISTFA 2016: Conference Proceedings from the 42nd International Symposium for Testing and Failure Analysis ◽

10.31399/asm.cp.istfa2016p0449 ◽

2016 ◽

Author(s):

Stuart Friedman ◽

Oskar Amster ◽

Yongliang Yang ◽

Fred Stanke

Keyword(s):

Process Development ◽

Advanced Characterization ◽

Electrical Measurement ◽

Depletion Layer ◽

Doped Semiconductors ◽

Force Microscopy ◽

Nano Scale ◽

Capacitance Voltage ◽

Systematic Response ◽

Lock In

Abstract The use of Atomic Force Microscopy (AFM) electrical measurement modes is a critical tool for the study of semiconductor devices and process development. A relatively new electrical mode, scanning microwave impedance microscopy (sMIM), measures a material’s change in permittivity and conductivity at the scale of an AFM probe tip [1]. sMIM provides the real and imaginary impedance (Re(Z) and Im(Z)) of the probe-sample interface. By measuring the reflected microwave signal as a sample of interest is imaged with an AFM, we can in parallel capture the variations in permittivity and conductivity and, for doped semiconductors, variations in the depletion-layer geometry. An existing technique for characterizing doped semiconductors, scanning capacitance microscopy, modulates the tip-sample bias and detects the tip-sample capacitance with a lock-in amplifier. A previous study compares sMIM to SCM and highlights the additional capabilities of sMIM [2], including examples of nano-scale capacitance-voltage curves. In this paper we focus on the detailed mechanisms and capabilities of the nano-scale C-V curves and the ability to extract semiconductor properties from them. This study includes analytical and finite element modeling of tip bias dependent depletion-layer geometry and impedance. These are compared to experimental results on reference samples for both doped Si and GaN doped staircases to validate the systematic response of the sMIM-C (capacitive) channel to the doping concentration.

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Free electron nonlinearities in heavily doped semiconductors plasmonics

Physical Review B ◽

10.1103/physrevb.103.115305 ◽

2021 ◽

Vol 103 (11) ◽

Author(s):

Federico De Luca ◽

Michele Ortolani ◽

Cristian Ciracì

Keyword(s):

Free Electron ◽

Doped Semiconductors ◽

Heavily Doped

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Overcoming the water oxidative limit for ultra-high-workfunction hole-doped polymers

Nature Communications ◽

10.1038/s41467-021-23347-x ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Qi-Mian Koh ◽

Cindy Guanyu Tang ◽

Mervin Chun-Yi Ang ◽

Kim-Kian Choo ◽

Qiu-Jing Seah ◽

...

Keyword(s):

Organic Semiconductors ◽

Water Oxidation ◽

Soft Materials ◽

Bulk Water ◽

Oxidation Potential ◽

Doped Semiconductors ◽

Good Thermal Stability ◽

Doped Polymers ◽

Super Acid ◽

Maximum Work

AbstractIt is widely thought that the water-oxidation reaction limits the maximum work function to about 5.25 eV for hole-doped semiconductors exposed to the ambient, constrained by the oxidation potential of air-saturated water. Here, we show that polymer organic semiconductors, when hole-doped, can show work functions up to 5.9 eV, and yet remain stable in the ambient. We further show that de-doping of the polymer is not determined by the oxidation of bulk water, as previously thought, due to its general absence, but by the counter-balancing anion and its ubiquitously hydrated complexes. The effective donor levels of these species, representing the edge of the ‘chemical’ density of states, can be depressed to about 6.0 eV below vacuum level. This can be achieved by raising the oxidation potential for hydronium generation, using large super-acid anions that are themselves also stable against oxidation. In this way, we demonstrate that poly(fluorene-alt-triarylamine) derivatives with tethered perfluoroalkyl-sulfonylimidosulfonyl anions can provide ambient solution-processability directly in the ultrahigh-workfunction hole-doped state to give films with good thermal stability. These results lay the path for design of soft materials for battery, bio-electronic and thermoelectric applications.

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