Doping Techniques in Emerging Semiconductors and Devices

A special issue of Micromachines (ISSN 2072-666X). This special issue belongs to the section "D:Materials and Processing".

Deadline for manuscript submissions: closed (31 October 2021) | Viewed by 17026

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The SDC Research Lab, Department of Electronic Engineering, Gachon University, 1342 Seongnam-daero, Seongnam 13120, Republic of Korea
Interests: 2D materials; nanodevices; nanomaterials; mixed-dimensional transistors; device physics; neuromorphic devices; integrated circuit; sensors; optoelectronic devices; organic semiconductors; memristors; floating-gate memories; charge traps; charge transports; carbon nanotubes; nanoscale devices; lithography; spectroscopies
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Special Issue Information

Dear Colleagues,

Over the past decade, emerging thin-film semiconductors such as transition-metal dichalcogenides (TMDs), carbon nanotubes, oxide, and organic materials have been intensively investigated as next-generation semiconducting materials owing to their excellent electrical, chemical, mechanical, and optical properties. However, conventional doping techniques such as ion-implantation damage these thin-film materials, and there is a great need to develop an alternative method to control the electrical properties.

This special issue calls for research papers, reviews, and short communications related to state-of-the-art developments that contribute to novel doping techniques for high-performance device applications.

Prof. Dr. Hocheon Yoo
Guest Editor

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Keywords

  • Two-dimensional materials
  • Oxide semiconductors
  • Doping mechanism
  • Organic dopants
  • Molecular and remote doping techniques
  • Dielectric interface
  • P-doping/n-doping
  • Charge transfer
  • Surface functionalization
  • Dipole-induced doping
  • Thin-film transistors
  • Contact doping
  • Work function engineering
  • Solution doping methods

Published Papers (5 papers)

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Research

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7 pages, 3375 KiB  
Article
Improvement of Fermi-Level Pinning and Contact Resistivity in Ti/Ge Contact Using Carbon Implantation
by Iksoo Park, Donghun Lee, Bo Jin, Jungsik Kim and Jeong-Soo Lee
Micromachines 2022, 13(1), 108; https://doi.org/10.3390/mi13010108 - 10 Jan 2022
Cited by 2 | Viewed by 1871
Abstract
Effects of carbon implantation (C-imp) on the contact characteristics of Ti/Ge contact were investigated. The C-imp into Ti/Ge system was developed to reduce severe Fermi-level pinning (FLP) and to improve the thermal stability of Ti/Ge contact. The current density (J)-voltage ( [...] Read more.
Effects of carbon implantation (C-imp) on the contact characteristics of Ti/Ge contact were investigated. The C-imp into Ti/Ge system was developed to reduce severe Fermi-level pinning (FLP) and to improve the thermal stability of Ti/Ge contact. The current density (J)-voltage (V) characteristics showed that the rectifying behavior of Ti/Ge contact into an Ohmic-like behavior with C-imp. The lowering of Schottky barrier height (SBH) indicated that the C-imp could mitigate FLP. In addition, it allows a lower specific contact resistivity (ρc) at the rapid thermal annealing (RTA) temperatures in a range of 450–600 °C. A secondary ion mass spectrometry (SIMS) showed that C-imp facilitates the dopant segregation at the interface. In addition, transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) mapping showed that after RTA at 600 °C, C-imp enhances the diffusion of Ge atoms into Ti layer at the interface of Ti/Ge. Thus, carbon implantation into Ge substrate can effectively reduce FLP and improve contact characteristics. Full article
(This article belongs to the Special Issue Doping Techniques in Emerging Semiconductors and Devices)
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14 pages, 2049 KiB  
Article
A-π-D-π-A-Based Small Molecules for OTFTs Containing Diketopyrrolopyrrole as Acceptor Units
by Baji Shaik, Mujeeb Khan, Mohammed Rafi Shaik, Mohammed A.F. Sharaf, Doumbia Sekou and Sang-Gyeong Lee
Micromachines 2021, 12(7), 817; https://doi.org/10.3390/mi12070817 - 13 Jul 2021
Cited by 1 | Viewed by 1881
Abstract
A-π-D-π-A-based small molecules 6,6′-((thiophene-2,5-diylbis(ethyne-2,1-diyl))bis(thiophene-5,2-diyl))bis(2,5-bis(2-ethylhexyl)-3-(thiophen-2-yl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione) (TDPP-T) and 6,6′-(((2,3-dihydrothieno[3,4-b][1,4]dioxine-5,7-diyl)bis(ethyne-2,1-diyl))bis(thiophene-5,2-diyl))bis(2,5-bis(2-ethylhexyl)-3-(thiophen-2-yl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione) (TDPP-EDOT) have been designed and synthesized. The diketopyrrolopyrrole acts as an electron acceptor, while the thiophene or 3,4-ethylenedioxythiophene acts as an electron donor. The donor–acceptor groups are connected by an ethynyl bridge to further enhance the [...] Read more.
A-π-D-π-A-based small molecules 6,6′-((thiophene-2,5-diylbis(ethyne-2,1-diyl))bis(thiophene-5,2-diyl))bis(2,5-bis(2-ethylhexyl)-3-(thiophen-2-yl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione) (TDPP-T) and 6,6′-(((2,3-dihydrothieno[3,4-b][1,4]dioxine-5,7-diyl)bis(ethyne-2,1-diyl))bis(thiophene-5,2-diyl))bis(2,5-bis(2-ethylhexyl)-3-(thiophen-2-yl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione) (TDPP-EDOT) have been designed and synthesized. The diketopyrrolopyrrole acts as an electron acceptor, while the thiophene or 3,4-ethylenedioxythiophene acts as an electron donor. The donor–acceptor groups are connected by an ethynyl bridge to further enhance the conjugation. The optoelectronics, electrochemical, and thermal properties have been investigated. Organic thin film transistor (OTFT) devices prepared from TDPP-T and TDPP-EDOT have shown p-type mobility. In as cast films, TDPP-T and TDPP-EDOT have shown a hole mobility of 5.44 × 10−6 cm2 V−1 s−1 and 4.13 × 10−6 cm2 V−1 s−1, respectively. The increase in the mobility of TDPP-T and TDPP-EDOT OTFT devices was observed after annealing at 150 °C, after which the mobilities were 3.11 × 10−4 cm2 V−1 s−1 and 2.63 × 10−4 cm2 V−1 s−1, respectively. Full article
(This article belongs to the Special Issue Doping Techniques in Emerging Semiconductors and Devices)
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11 pages, 2541 KiB  
Article
Bulk versus Contact Doping in Organic Semiconductors
by Chang-Hyun Kim
Micromachines 2021, 12(7), 742; https://doi.org/10.3390/mi12070742 - 24 Jun 2021
Cited by 4 | Viewed by 2655
Abstract
This study presents a comparative theoretical analysis of different doping schemes in organic semiconductor devices. Especially, an in-depth investigation into bulk and contact doping methods is conducted, focusing on their direct impact on the terminal characteristics of field-effect transistors. We use experimental data [...] Read more.
This study presents a comparative theoretical analysis of different doping schemes in organic semiconductor devices. Especially, an in-depth investigation into bulk and contact doping methods is conducted, focusing on their direct impact on the terminal characteristics of field-effect transistors. We use experimental data from a high-performance undoped organic transistor to prepare a base simulation framework and carry out a series of predictive simulations with various position- and density-dependent doping conditions. Bulk doping is shown to offer an overall effective current modulation, while contact doping proves to be rather useful to overcome high-barrier contacts. We additionally demonstrate the concept of selective channel doping as an alternative and establish a critical understanding of device performances associated with the key electrostatic features dictated by interfaces and applied voltages. Full article
(This article belongs to the Special Issue Doping Techniques in Emerging Semiconductors and Devices)
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9 pages, 3152 KiB  
Communication
Remote Doping Effects of Indium–Gallium–Zinc Oxide Thin-Film Transistors by Silane-Based Self-Assembled Monolayers
by Juhyung Seo and Hocheon Yoo
Micromachines 2021, 12(5), 481; https://doi.org/10.3390/mi12050481 - 23 Apr 2021
Cited by 9 | Viewed by 2904
Abstract
Oxide thin-film transistors (TFTs), including indium–gallium–zinc oxide (IGZO) TFTs, have been widely investigated because of their excellent properties, such as compatibility with flexible substrates, high carrier mobility, and easy-to-fabricate TFT processes. However, to increase the use of oxide semiconductors in electronic products, an [...] Read more.
Oxide thin-film transistors (TFTs), including indium–gallium–zinc oxide (IGZO) TFTs, have been widely investigated because of their excellent properties, such as compatibility with flexible substrates, high carrier mobility, and easy-to-fabricate TFT processes. However, to increase the use of oxide semiconductors in electronic products, an effective doping method that can control the electrical characteristics of oxide TFTs is required. Here, we comprehensively investigate the effect of silane-based self-assembled monolayer (SAM) doping on IGZO TFTs. Instead of a complex doping process, the electrical performance can be enhanced by anchoring silane-based SAMs on the IGZO surface. Furthermore, differences in the doping effect based on the structure of SAMs were analyzed; the analysis offers a systematic guideline for effective electrical characteristic control in IGZO TFTs. Full article
(This article belongs to the Special Issue Doping Techniques in Emerging Semiconductors and Devices)
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Review

Jump to: Research

17 pages, 3932 KiB  
Review
Self-Assembled Monolayers: Versatile Uses in Electronic Devices from Gate Dielectrics, Dopants, and Biosensing Linkers
by Seongjae Kim and Hocheon Yoo
Micromachines 2021, 12(5), 565; https://doi.org/10.3390/mi12050565 - 17 May 2021
Cited by 21 | Viewed by 6508
Abstract
Self-assembled monolayers (SAMs), molecular structures consisting of assemblies formed in an ordered monolayer domain, are revisited to introduce their various functions in electronic devices. SAMs have been used as ultrathin gate dielectric layers in low-voltage transistors owing to their molecularly thin nature. In [...] Read more.
Self-assembled monolayers (SAMs), molecular structures consisting of assemblies formed in an ordered monolayer domain, are revisited to introduce their various functions in electronic devices. SAMs have been used as ultrathin gate dielectric layers in low-voltage transistors owing to their molecularly thin nature. In addition to the contribution of SAMs as gate dielectric layers, SAMs contribute to the transistor as a semiconducting active layer. Beyond the transistor components, SAMs have recently been applied in other electronic applications, including as remote doping materials and molecular linkers to anchor target biomarkers. This review comprehensively covers SAM-based electronic devices, focusing on the various applications that utilize the physical and chemical properties of SAMs. Full article
(This article belongs to the Special Issue Doping Techniques in Emerging Semiconductors and Devices)
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