Innovative Methods for Semiconductor Doping

A special issue of Micro (ISSN 2673-8023). This special issue belongs to the section "Microscale Materials Science".

Deadline for manuscript submissions: closed (31 October 2023) | Viewed by 22301

Special Issue Editors


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Guest Editor
Institute for Microelectronics and Microsystems, National Research Council, Strada Ottava 5 Z.I., 95121 Catania, Italy
Interests: silicon; nanostructures; nanotechnologies; silicon based optoelectronic devices; enhanced light–matter interaction
Special Issues, Collections and Topics in MDPI journals
Department of Mechanical and Electrical Engineering, University of Southern Denmark, Alsion 2, 6400 Sønderborg, Denmark
Interests: computational and mathematical modelling for photonic materials and structures; sensing; energy conversion; lighting
Special Issues, Collections and Topics in MDPI journals
Tyndall National Institute, University College Cork, T12 R5CP Cork, Ireland
Interests: emerging materials and devices for future nanoelectronic; ICT; sensing and quantum applications; encompassing fabrication, characterisation and modelling of nanowire and thin film devices

Special Issue Information

Dear Colleagues,

We are glad to present this Special Issue of the Journal Micro, entitled: "Innovative methods for semiconductor doping." Its objective is to provide up-to-date, relevant references on the advanced doping techniques for semiconductors currently under investigation by the scientific and industrial communities. The International Roadmap for Devices and Systems (IRDS™) has requested advanced concepts for higher performance and energy efficient devices. As far as scaling is concerned, new device architectures such as double or tri-gate and nanowires or nanosheets have been introduced. Fin field-effect transistors have already become mainstream, but the technology still requests other vertical gate-all-around architecture advancements. The challenges in pursuing these objectives are the inability to obtain conformality through the conventional doping methods, the surface defect effects, the dopant activation, and the losses due to the parasitic resistances. Many of these effects compromise the high-mobility benefits of the vertical structure, undermining these new approaches' technological relevance. In this perspective, new paradigms in alternative doping solutions have been developed, such as monolayer doping, laser annealing, plasma-based processes, to name a few. These new advances' maturity level is up to lab-scale device application, but still, many aspects need improvement and deeper studies for the very large-scale integration (VLSI). Another current interest in higher performance versus energy efficiency is related to silicon carbide doping, widely used in high power devices. Here, the open challenges for the in-situ and ex-situ cases are the high-temperature activation processes, incomplete dopant ionization, dopant profiling, ohmic contact formation, impurity lattice location, as well as lattice distortions. Many of the concepts listed so far refer to inorganic semiconductors and their alloys. A rising interesting field is doping in organic semiconductors. The doping concepts differ significantly for inorganic and organic semiconductors due to fundamental differences in, e.g., transport and electron-hole generation mechanisms. In organics, doping has been mostly excluded mainly for the uncontrollable diffusion. As a result, organic electronics currently suffer from low performance and manufacturing difficulties. Breakthroughs in doping organic semiconductors have, however, demonstrated that doping is key to enable high‐performance. The fundamentals in doping basics, mechanisms and techniques, the phenomena observed, and the doping role in the desired electrical characteristics are currently open issues. With the introduction of these approaches in organic and inorganic semiconductors, simulations from ab-initio to TCAD can help explore the new options by designing and assisting experiments.

This Special Issue will welcome high quality experimental and modeling studies on the above-mentioned developments in advanced semiconductor doping techniques. The list of key topics is reported in the following:

  • Different Substrates (Si, SiC, Ge, SiGe, InGaAs, GaP, organic materials...)
  • Doping Technologies and Processes: Ion Implantation, Plasma Doping, Molecular, Gas and Solid Doping.
  • Annealing Technologies and Processes: Rapid Thermal Processing, Laser Annealing, Flash Annealing, SPE, Silicide, Contact and Dielectric Formation, Lattice Damage and Defect
  • Device Applications: CMOS, Memory, Power (SiC, GaN), RF-SOI, Image Sensors, IoT Devices, Photovoltaics, III-V Devices
  • Metrologies: Chemical, Physical and Electrical Characterization of 2D and 3D Structures
  • Modeling and Simulations (from ab-initio to TCAD) of all of the above.

Dr. Rosaria A. Puglisi
Dr. Jost Adam
Dr. Ray Duffy
Guest Editors

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Keywords

  • semiconductors
  • doping technology
  • annealing technology
  • device application
  • metrology
  • simulations

Published Papers (5 papers)

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Research

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13 pages, 5107 KiB  
Article
Highly Sensitive Sensor for the Determination of Riboflavin Using Thionine Coated Cadmium Selenide Quantum Dots Modified Graphite Electrode
by Arumugam Kalaivani, Rajendran Suresh Babu and Sangilimuthu Sriman Narayanan
Micro 2023, 3(3), 686-698; https://doi.org/10.3390/micro3030048 - 13 Aug 2023
Cited by 1 | Viewed by 1063
Abstract
In this paper, the electrochemical non-enzymatic detection of Riboflavin (RF) was proposed based on its catalytic reduction in a Thionine-coated Cadmium Selenide Quantum dots (TH@CdSe QDs)-modified paraffin wax-impregnated graphite electrode (PIGE) that was prepared using a novel approach. The synthesized TH@CdSe QDs were [...] Read more.
In this paper, the electrochemical non-enzymatic detection of Riboflavin (RF) was proposed based on its catalytic reduction in a Thionine-coated Cadmium Selenide Quantum dots (TH@CdSe QDs)-modified paraffin wax-impregnated graphite electrode (PIGE) that was prepared using a novel approach. The synthesized TH@CdSe QDs were confirmed by UV-Vis spectroscopy, Confocal Raman Microscopy and High Resolution Transmission Electron Microscopy (HRTEM) studies. The electrochemical response of the TH@CdSe QDs-modified PIGE was studied by cyclic voltammetry. The voltammetric response of RF at the TH@CdSe QDs-modified PIGE showed higher current than the bare PIGE. Under optimum conditions, the electrocatalytic reduction currents of RF was found to be linearly related to its concentration over the range of 1.6 × 10−7 M to 1.4 × 10−4 M with a detection limit of 53 × 10−9 M (S/N = 3). The TH@CdSe QDs-modified PIGE was utilized as an amperometric sensor for the detection of RF in flow systems was performed by carrying out hydrodynamic and chronoamperometric experiments. The TH@CdSe QDs-modified PIGE showed very good stability and a longer shelf life. The applicability of the fabricated electrode was justified by the quantification of RF in commercial tablets. Full article
(This article belongs to the Special Issue Innovative Methods for Semiconductor Doping)
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11 pages, 3261 KiB  
Article
Sacrificial Doping as an Approach to Controlling the Energy Properties of Adsorption Sites in Gas-Sensitive ZnO Nanowires
by Svetlana Nalimova, Zamir Shomakhov, Anton Bobkov and Vyaсheslav Moshnikov
Micro 2023, 3(2), 591-601; https://doi.org/10.3390/micro3020040 - 01 Jun 2023
Cited by 2 | Viewed by 1013
Abstract
Currently, devices for environmental gas analyses are required in many areas of application. Among such devices, semiconductor-resistive gas sensors differ advantageously. However, their characteristics need further improvement. The development of methods for controlling the surface properties of nanostructured metal oxides for their use [...] Read more.
Currently, devices for environmental gas analyses are required in many areas of application. Among such devices, semiconductor-resistive gas sensors differ advantageously. However, their characteristics need further improvement. The development of methods for controlling the surface properties of nanostructured metal oxides for their use as gas sensors is of great interest. In this paper, a method involving the sacrificial doping of ZnO nanowires to control the content of their surface defects (oxygen vacancies) was proposed. Zinc oxide nanowires were synthesized using the hydrothermal method with sodium iodide or bromide as an additional precursor. The surface composition was studied using X-ray photoelectron spectroscopy. The sensor properties of the isopropyl alcohol vapors at 150 °C were studied. It was shown that a higher concentration of oxygen vacancies/hydroxyl groups was observed on the surfaces of the samples synthesized with the addition of iodine and bromine precursors compared to the pure zinc oxide nanowires. It was also found out that these samples were more sensitive to isopropyl alcohol vapors. A model was proposed to explain the appearance of additional oxygen vacancies in the subsurface layer of the zinc oxide nanowires when sodium iodide or sodium bromide was added to the initial solution. The roles of oxygen vacancies and surface hydroxyl groups in providing the samples with an increased sensitivity were explained. Thus, a method involving the sacrificial doping of zinc oxide nanowires has been developed, which led to an improvement in their gas sensor characteristics due to an increase in the concentration of oxygen vacancies on their surface. The results are promising for percolation gas sensors equipped with additional water vapor traps that work stably in a high humidity. Full article
(This article belongs to the Special Issue Innovative Methods for Semiconductor Doping)
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14 pages, 13700 KiB  
Article
Silicon Nitride Interface Engineering for Fermi Level Depinning and Realization of Dopant-Free MOSFETs
by Benjamin Richstein, Lena Hellmich and Joachim Knoch
Micro 2021, 1(2), 228-241; https://doi.org/10.3390/micro1020017 - 21 Nov 2021
Cited by 7 | Viewed by 5251
Abstract
Problems with doping in nanoscale devices or low temperature applications are widely known. Our approach to replace the degenerate doping in source/drain (S/D)-contacts is silicon nitride interface engineering. We measured Schottky diodes and MOSFETs with very thin silicon nitride layers in between silicon [...] Read more.
Problems with doping in nanoscale devices or low temperature applications are widely known. Our approach to replace the degenerate doping in source/drain (S/D)-contacts is silicon nitride interface engineering. We measured Schottky diodes and MOSFETs with very thin silicon nitride layers in between silicon and metal. Al/SiN/p-Si diodes show Fermi level depinning with increasing SiN thickness. The diode fabricated with rapid thermal nitridation at 900 C reaches the theoretical value of the Schottky barrier to the conduction band ΦSB,n=0.2 eV. As a result, the contact resistivity decreases and the ambipolar behavior can be suppressed. Schottky barrier MOSFETs with depinned S/D-contacts consisting of a thin silicon nitride layer and contact metals with different work functions are fabricated to demonstrate unipolar behavior. We presented n-type behavior with Al and p-type behavior with Co on samples which only distinguish by the contact metal. Thus, the thermally grown SiN layers are a useful method suppress Fermi level pinning and enable reconfigurable contacts by choosing an appropriate metal. Full article
(This article belongs to the Special Issue Innovative Methods for Semiconductor Doping)
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31 pages, 3967 KiB  
Review
Ion Implantation Doping in Silicon Carbide and Gallium Nitride Electronic Devices
by Fabrizio Roccaforte, Filippo Giannazzo and Giuseppe Greco
Micro 2022, 2(1), 23-53; https://doi.org/10.3390/micro2010002 - 10 Jan 2022
Cited by 15 | Viewed by 9171
Abstract
Wide band gap semiconductors such as silicon carbide (SiC) and gallium nitride (GaN) are excellent materials for the next generation of high-power and high-frequency electronic devices. In fact, their wide band gap (>3 eV) and high critical electric field (>2 MV/cm) enable superior [...] Read more.
Wide band gap semiconductors such as silicon carbide (SiC) and gallium nitride (GaN) are excellent materials for the next generation of high-power and high-frequency electronic devices. In fact, their wide band gap (>3 eV) and high critical electric field (>2 MV/cm) enable superior performances to be obtained with respect to the traditional silicon devices. Hence, today, a variety of diodes and transistors based on SiC and GaN are already available in the market. For the fabrication of these electronic devices, selective doping is required to create either n-type or p-type regions with different functionalities and at different doping levels (typically in the range 1016–1020 cm−3). In this context, due to the low diffusion coefficient of the typical dopant species in SiC, and to the relatively low decomposition temperature of GaN (about 900 °C), ion implantation is the only practical way to achieve selective doping in these materials. In this paper, the main issues related to ion implantation doping technology for SiC and GaN electronic devices are briefly reviewed. In particular, some specific literature case studies are illustrated to describe the impact of the ion implantation doping conditions (annealing temperature, electrical activation and doping profiles, surface morphology, creation of interface states, etc.) on the electrical parameters of power devices. Similarities and differences in the application of ion implantation doping technology in the two materials are highlighted in this paper. Full article
(This article belongs to the Special Issue Innovative Methods for Semiconductor Doping)
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22 pages, 4407 KiB  
Review
Electrical and Optical Doping of Silicon by Pulsed-Laser Melting
by Shao Qi Lim and James S. Williams
Micro 2022, 2(1), 1-22; https://doi.org/10.3390/micro2010001 - 24 Dec 2021
Cited by 10 | Viewed by 3818
Abstract
Over four decades ago, pulsed-laser melting, or pulsed-laser annealing as it was termed at that time, was the subject of intense study as a potential advance in silicon device processing. In particular, it was found that nanosecond laser melting of the near-surface of [...] Read more.
Over four decades ago, pulsed-laser melting, or pulsed-laser annealing as it was termed at that time, was the subject of intense study as a potential advance in silicon device processing. In particular, it was found that nanosecond laser melting of the near-surface of silicon and subsequent liquid phase epitaxy could not only very effectively remove lattice disorder following ion implantation, but could achieve dopant electrical activities exceeding equilibrium solubility limits. However, when it was realised that solid phase annealing at longer time scales could achieve similar results, interest in pulsed-laser melting waned for over two decades as a processing method for silicon devices. With the emergence of flat panel displays in the 1990s, pulsed-laser melting was found to offer an attractive solution for large area crystallisation of amorphous silicon and dopant activation. This method gave improved thin film transistors used in the panel backplane to define the pixelation of displays. For this application, ultra-rapid pulsed laser melting remains the crystallisation method of choice since the heating is confined to the silicon thin film and the underlying glass or plastic substrates are protected from thermal degradation. This article will be organised chronologically, but treatment naturally divides into the two main topics: (1) an electrical doping research focus up until around 2000, and (2) optical doping as the research focus after that time. In the first part of this article, the early pulsed-laser annealing studies for electrical doping of silicon are reviewed, followed by the more recent use of pulsed-lasers for flat panel display fabrication. In terms of the second topic of this review, optical doping of silicon for efficient infrared light detection, this process requires deep level impurities to be introduced into the silicon lattice at high concentrations to form an intermediate band within the silicon bandgap. The chalcogen elements and then transition metals were investigated from the early 2000s since they can provide the required deep levels in silicon. However, their low solid solubilities necessitated ultra-rapid pulsed-laser melting to achieve supersaturation in silicon many orders of magnitude beyond the equilibrium solid solubility. Although infrared light absorption has been demonstrated using this approach, significant challenges were encountered in attempting to achieve efficient optical doping in such cases, or hyperdoping as it has been termed. Issues that limit this approach include: lateral and surface impurity segregation during solidification from the melt, leading to defective filaments throughout the doped layer; and poor efficiency of collection of photo-induced carriers necessary for the fabrication of photodetectors. The history and current status of optical hyperdoping of silicon with deep level impurities is reviewed in the second part of this article. Full article
(This article belongs to the Special Issue Innovative Methods for Semiconductor Doping)
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