Search query: Wide Bandgap Oxide Semiconductors: from Materials Physics to Optoelectronic Devices

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abstract: Wide bandgap oxide semiconductors constitute a unique class of materials that combine properties of electrical conductivity and optical transparency. They are being widely used as key materials in optoelectronic device applications, including flat panel displays, solar cells, OLED, and emerging flexible and transparent electronics. In this article, an up to date review on both the fundamental understanding of materials physics of oxide semiconductors, and recent research progress on design of new materials and high performing thin film transistor (TFT) devices in the context of fundamental understanding is presented. In particular, an in depth overview is first provided on current understanding of the electronic structures, defect and doping chemistry, optical and transport properties of oxide semiconductors, which provide essential guiding principles for new material design and device optimization. With these principles, recent advances in design of p type oxide semiconductors, new approaches for achieving cost effective transparent (flexible) electrodes, and the creation of high mobility 2D electron gas (2DEG) at oxide surfaces and interfaces with a wealth of fascinating physical properties of great potential for novel device design are then reviewed. Finally, recent progress and perspective of oxide TFT based on new oxide semiconductors, 2DEG, and low temperature solution processed oxide semiconductor for flexible electronics will be reviewed.
author_names: Jueli Shi

Jiaye Zhang

Luhan Yang

Mei Qu

Dong-chen Qi

Kelvin H L Zhang
title: Wide Bandgap Oxide Semiconductors: from Materials Physics to Optoelectronic Devices.
venue: Advanced materials
year: 2021

abstract: II oxides wide bandgap semiconductor, including the beryllium oxide (BeO) magnesium oxide (MgO) zinc oxide (ZnO) have large exciton binding energy (ZnO 60 meV, MgO 80 meV) high optical gain (ZnO 300 cm 1) and wide tunable band gap (3.37 eV ZnO, MgO 7.8 eV, BeO 10.6 eV) which are the advantages of achieving low threshold laser devices in the ultraviolet wavelength. It is also one of the important candidates to replace the traditional gas arc lamp (such as mercury lamp, deuterium lamp, excimer lamp, xenon lamp etc. as the source of deep ultraviolet and even vacuum ultraviolet. Although, during the past decades, the ZnO based pn homojunction devices have made great progress in the near UV electroluminescence, but as the band gap broadens, the acceptor (or donor) ionization energy becomes higher (On the order of hundreds meV) which causing the room temperature equivalent thermal energy (26 meV) cannot make the impurities ionizing effectively. In addition, the self compensation effect in the doping process further weakens the carrier yield. These above drawbacks have become the bottleneck that hinders II oxides wide bandgap semiconductor from achieving ultraviolet laser devices and expanding to shorter wavelengths, and are also a common problem faced by other wide bandgap semiconductor materials. The regulation of the electrical and luminescent properties of materials often depends on the control of critical defect states. The rich point defects and their combination types make the II oxides wide bandgap semiconductors an important platform for studying defect physics. For the identification and characterization of specific point defects, it is expected to discover and further construct shallower defect states, which will provide a basis for the regulation of electrical performance. In this paper, recent research results of II oxides wide bandgap semiconductors will be described from three aspects: high quality epitaxial growth, impurity and point defects, p type doping and ultraviolet electroluminescence. Through the overview of related research works, II oxides wide bandgap semiconductors are clarified as deep ultraviolet light sources materials. Meanwhile, indicates that the key to the regulation of electrical performance in the future lies in the regulation of point defects.
author_names: Xie Xiu-hua

Liao Bing-hui

Zhang Zhen-zhong

Liu Lei

Liu Ke-Wei

Shan Chong-Xin

Shen De-zhen
title: Point defects: key issues for II oxides wide bandgap semiconductors development
year: 2019

abstract: Energy has emerged to be a global concern as the world confronts the challenges of population growth, climate change, economic recovery, energy affordability. To overcome the energy crisis, people need to work with both hands: use one hand to make a transition from fossil fuels to clean, renewable energy and the other hand to cut down energy consumption by developing energy efficient devices and systems. In this dissertation, I focus my research to tackle these problems using wide bandgap semiconductors, III nitride (GaN and InGaN) and zinc oxide (ZnO) as basic materials due to their unique optoelectronic properties. Material growth III nitride using MOCVD and ZnO using hydrothermal solution synthesis are studied. For renewable energy application, I developed InGaN/GaN MQW photoelectrode for spontaneous photoelectrochemical (PEC) water splitting and hydrogen fuel generation. The InGaN/ GaN MQW structure provides sufficient photovoltage to split water. Using this single photoelectrode, a current density of 0.16 mA*cm 2 and a peak solar to hydrogen conversion efficiency of 0.2% are obtained at zero external bias. Two schemes are studied to improve the photoelectrode efficiency and stability. By adding NiOx oxygen evolution catalyst, the overall solar to hydrogen conversion efficiency is improved to 0.64% at zero bias. The stability of photoelectrode is also much improved and photocurrent reduction of 4.5% in 12 hours is achieved. In order to further boost the performance of the photoelectrode, plasmonic metal nanostructures are created for enhanced light absorption. The conversion efficiency is improved up to 0.93% For energy saving application, I demonstrated a novel lighting technology based on nano materials ZnO nanowires and carbon nanotubes. The novel design, junctionless light emitting device, consists of a carbon nanotube array cathode for electron field emission and a ZnO nanowire array light emitting anode. High energy electrons directly bombard onto nanowires, generate electron hole pairs, which subsequently recombine to emit light. Strong near band edge emission is obtained with a peak at 390 nm. The use of vertical nanowire array as anode offers advantages in increasing the junction area and carrier recombination/photon generation and enhancing the light extraction efficiency. This approach utilizes the unique properties of nanoscale materials and opens an area for efficient lighting technologies in the future
author_names: Muchuan Yang
title: Wide bandgap semiconductors for energy efficiency and renewable energy applications
year: 2014

abstract: Nitrides feature many interesting properties, such as a wide range of bandgaps suitable for optoelectronic devices including light emitting diodes (LEDs) and piezoelectric response used in microelectromechanical systems (MEMS) Nitrides are also significantly underexplored compared to oxides and other chemistries, with many being thermochemically metastable, sparking interest from a basic science point of view. This paper reports on experimental and computational exploration of the Mg Sb N material system, featuring both metastable materials and interesting semiconducting properties. Using sputter deposition, we discovered a new Mg2SbN3 nitride with a wurtzite derived crystal structure and synthesized the antimonide nitride Mg3SbN with an antiperovskite crystal structure for the first time in thin film form. Theoretical calculations indicate that Mg2SbN3 is metastable and has properties relevant to LEDs and MEMS, whereas Mg3SbN has a large dielectric constant (28\epsilon_0) and low hole effective masses (0.9m_0) of interest for photovoltaic solar cell absorbers. The experimental solar matched 1.3 eV optical absorption onset of the Mg3SbN antiperovskite agrees with the theoretical prediction (1.3 eV direct, 1.1 eV indirect) and with the measurements of room temperature near bandgap photoluminescence. These results make an important contribution towards understanding semiconductor properties and chemical trends in the Mg Sb N materials system, paving the way to future practical applications of these novel materials.
author_names: Karen N Heinselman

Stephan Lany

John D Perkins

Kevin R Talley

Andriy Zakutayev
title: Thin Film Synthesis of Semiconductors in the Mg Sb N Materials System
venue: Chemistry of Materials
year: 2019

abstract: b Ga2O3 is an emerging, ultra wide bandgap (energy gap of 4.85 eV) transparent semiconducting oxide (TSO) which attracted recently much scientific and technological attention. Unique properties of that compound combined with its advanced development in growth and characterization place b Ga2O3 in the frontline of future applications in electronics (Schottky barrier diodes, field effect transistors) optoelectronics (solar and visible blind photodetectors, flame detectors, light emitting diodes) and sensing systems (gas sensors, nuclear radiation detectors) A capability of growing large bulk single crystals directly from the melt and epi layers by a diversity of epitaxial techniques, as well as explored material properties and underlying physics, define a solid background for a device fabrication, which, indeed, has been boosted in recent years. This required, however, enormous efforts in different areas of science and technology that constitutes a chain linking together engineering, metrology and theory. The present review includes material preparation (bulk crystals, epi layers, surfaces) an exploration of optical, electrical, thermal and mechanical properties, as well as device design fabrication with resulted functionality suitable for different fields of applications. The review summarizes all of these aspects of b Ga2O3 at the research level that spans from the material preparation through characterization to final devices.
author_names: Zbigniew Galazka
title: b Ga2O3 for wide bandgap electronics and optoelectronics
year: 2018

abstract: Ultraviolet (UV) photodetectors (PDs) as pivotal elements in modern optoelectronic devices, have attracted increasing research interest in recent years because of their wide applications both in civil and military fields such as confidential space communication, flame detection, imaging, and missile warning systems. Gallium oxide is a desirable candidate for deep UV photodetection due to its suitable ultrawide bandgap 4.5 to 4.9 eV) without the necessity of alloying process. It is reported that crystalline gallium oxide has five phases (a, b, g, d and e) and b phase is the most stable. Many kinds of crystalline gallium oxide UV PDs including bulk, thin films, and nanostructures have been demonstrated and summarized in several review articles recently. According to common understanding of semiconductors, properties of crystalline materials with limited defects are usually superior compared with their amorphous counterparts. For example, the performance of solar cells or transistors using crystalline Si is better than amorphous ones because the carrier mobility of crystalline Si is about 200 cm V 1 s which is much higher than the value of amorphous Si 1 cm V 1 s However, things have been changed in 2004, since the first report of high performance flexible thin film transistors (TFTs) based on amorphous InGaZnO (a IGZO) a transparent amorphous oxide semiconductor (TAOS) with electron mobility as high as 10 cm V 1 s From then on, TAOS TFTs as well as the fundamental material science have been extensively investigated and now they are being used in commercial large area flat panel displays. According to previous researches related with a IGZO, Ga element is a necessary stabilizer in the amorphous structure since gallium oxide will not crystallize unless the substrate temperature is higher enough, whereas indium oxide and zinc oxide tend to crystallize readily even at room temperature (RT) It indicates amorphous gallium oxide (a GaOx) could be realized more easily compared with indium oxide and zinc oxide. As a matter of fact, a GaOx has also attracted a great deal of attention due to its wide bandgap and high breakdown field strength. At the earlier stage, a GaOx thin films were mainly used as a dielectric layer or a passivation layer in microelectronic devices and solar cells. In 2017, three groups reported solar blind UV PDs using a GaOx thin films almost simultaneously. It is quite interesting that the performance of UV PD using a GaOx is comparable or even better than its crystalline counterpart. Except for UV PDs, a GaOx materials also have extensive applications in areas of solar cells, phosphors, resistance random access memories (RRAMs) gas sensors, and radiation detectors. These versatile applications together with the fact that scalable a GaOx can be easily prepared on almost any substrates make it appealing for flexible electronics and giant microelectronics. Great attention has been paid to this cost effective material, evidenced by the increased number of publications retrieved with the key word of "amorphous Ga2O3," as shown in Figure 1. To further understand the material properties of a GaOx and construct superior UV PDs, it is necessary to summarize the progresses on a GaOx materials and devices. In this Review, we will Dr. H. Liang, Z. Han, Prof. Z. Mei Songshan Lake Materials Laboratory Dongguan, Guangdong 523808, China E mail: hlliang@iphy.ac.cn; zxmei@iphy.ac.cn Dr. H. Liang, Z. Han, Prof. Z. Mei Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100190, China Z. Han School of Physical Sciences University of Chinese Academy of Sciences Beijing 100049, China
author_names: Huili Liang

Zuyin Han

Zengxia Mei
title: Recent Progress of Deep Ultraviolet Photodetectors using Amorphous Gallium Oxide Thin Films
venue: physica status solidi (a)
year: 2020

abstract: In this article density functional theory (DFT) approach is utilized to study the crystal structure and optoelectronic properties of the double perovskites Ba2MM'O6 (M= Sc, Y, La; M' Nb, Ta) in cubic phase with space group Fm 3m (No. 225) Generalized gradient approximation along with modified Becke Johnson exchange potential is used to investigate the optoelectronic properties of these transition metal based compounds. The calculated electronic band profiles show that all these oxides are wide and direct bandgap semiconductors. The bandgaps of the oxides ranges from 3.8 to 4.7 eV. Optical properties demonstrate many aspects due to their potential applications as dielectric materials and in optoelectronic devices.
author_names: Shahid Mehmood

Zahid Ali
title: Optoelectronic properties of the double perovskites Ba2MM'O6 (M= Sc, Y, La; M' Nb, Ta) by modified Becke Johnson potential
venue: Other Conferences
year: 2020

abstract: The UV community for the fourth time took part in the International Workshop on Ultraviolet Materials and Devices (IWUMD4) which was organized in September 2019 by the Ioffe Institute, St. Petersburg, Russia. This event, following the successful meetings in Beijing, China (2016) Fukuoka, Japan (2017) Kunming, China (2018) was intended to show new horizons beyond the UV blue LEDs based on wide bandgap III Nitrides. Material science, modeling and technology for the "UV gap" (200 300 nm) are at the frontier of applied physics. The studies are aimed at developing devices for such areas as medicine for human safely disinfection and rapid detection of viral threats, communication for noise protected and solar blind UV optical communication, nanotechnology for high resolution photolithography and for many other applications in the field of biology, pharmaceuticals and forensics. The Workshop was attended by 125 scientists from 15 coun tries, including half from Asia and half from Europe and the DOI: 10.1002/pssa.202000378 USA. The Program was very eventful and included 2 plenary talks by Prof. Chris G. Van de Walle (UCSB) and Prof. Michael Kneissl (TU Berlin&FBH) 4 keynotes, and 25 invited papers, as well as 35 oral presentations and 36 poster contributions displayed during two poster sessions. Prior to Workshop, the Tutorials on the basic properties of wide gap semiconductor materials and nanostructures with lectures of outstanding experts in this field were held for one and a half days. The scope of the presentations at the Workshop was quite wide. Besides the fundamental properties of wide gap semiconductor materials and nanostructures, their optical and structural characterization and applications, it highlighted new trends, such as the growth, basic properties and applications of Ga2O3 and physics of BN from bulk to 2D materials. This issue features selected reports from the Workshop participants. Recent results on the manufacture of high quality templates of the nitrides and oxides by using different technological approaches are presented. The fundamental problems of low dimensional heterostructures and the techno logical challenges of various epitaxial growth methods, such as molecular beam epitaxy and metalorganic chemical vapor deposition, are examined in detail to further improve the quan tum efficiency and output power of UV light emitting devices. A study of the optical properties of AlGaN layers and laser diode heterostructures are presented, which elucidate the nature and characteristics of spontaneous and stimulated emis sions in AlGaN laser structures. In addition, the fabrication and radiation of GaN hexagonal microcavities are discussed. A variety of topics reflects the wide range of interests of the Workshop. The Editors would like to thank all the members of the International Advisory and Program Committees for their encouragement and great help during the Workshop organization. We are grateful to the referees for their efforts and time devoted to the paper review process. We owe our best thanks to the official partners and sponsors of the workshop, as well as all participants at the symposium exhibition. Finally, we would like to express our sincere gratitude to Dr. Stefan Hildebrandt and the production team of physica status solidi for their friendly assistance and collaboration in the editorial process. The next 5th International Workshop on Ultraviolet Materials and Devices (IWUMD5) is planned to be held in November 2020 in Jeju, Korea. We wish the organizers a gorgeous and successful meeting.
author_names: Stefan Ivanov

Tatiana V Shubina

Valentin N Jmerik

Bernard Gil
title: Ultraviolet Materials and Devices
year: 2020

abstract: II VI semiconductors (compounds formed by group IIB metallic elements (Cd, Zn, and Hg) with group VI nonmetallic elements (O, S, Se, and Te) have aroused intense interest in research and development. Because of its prominent optoelectronic properties for applications such as in thin film photovoltaics, nanophotodetectors, and lasers, cadmium sulfide (CdS) has been in the spotlight. Due to its unique properties and applications in nanoscience and nanotechnology as phosphors, sensors, and optoelectronic devices, zinc oxide (ZnO) has drawn the attention as a strategic and safe technological material. Moreover, on account of their unique capability of behaving as both wide bandgap (1.5 3.5 eV) and narrow bandgap (0 1.5 eV) materials, II VI compounds are utilized in applications such as photoconductors, ultrasonic transducers, and Hall effect devices. Mercury telluride (HgTe) has been placed in the foreground due to its very high Hall mobility and mobility ratio. In this chapter, a description of the processing techniques, properties, and applications of CdS, ZnO, and HgTe (and related ternary and quaternary compounds) both as thin films and nanostructured forms, is detailed. Studies on the resulting materials morphologies and optoelectronic properties from previous works by other authors as well as from the authors' investigations mainly focusing on CdS prepared by the chemical bath deposition (CBD) technique, are presented. The chapter is also intended to provide the readers with both seminal and recent bibliographical references on the topics.
author_names: Bindu Krishnan

Sadasivan Shaji

M C Acosta-Enriquez

E B Acosta-Enriquez

R Castillo-Ortega

Ma E Zayas

S Jesus Castillo

Ilaria Elena Palama

E D'Amone

Martin Ignacio Pech-Canul

Stefania D'Amone

Barbara Cortese
title: Group II VI Semiconductors
year: 2019

abstract: Wide bandgap semiconductors such as SiC, GaN and related alloys, BN and related alloys, ZnGeSiN2, ZnO, and others continue to find new applications in solid state lighting, sensors, filters, high power electronics, biological detection, and spintronics. Improved bulk and epitaxial growth, processing, device design, and understanding of the physics of transport in heterostructures are all necessary for realization of these new technologies. The papers in this book span a range of subjects from material growth and characterization to the processing and application of devices in the electronic, as well as the optoelectronic, fields. Topics include: special invited papers; growth, processing and devices; novel applications for wide bandgap semiconductors; oxides, heterostructures and devices; processing and devices and emerging areas.
author_names: Jen-Inn Chyi

Stephen J Pearton

Jung Jae Han

Albert G Baca

W H Chang
title: New applications for wide bandgap semiconductors symposium held April 22 24, 2003, San Francisco, California, U.S.A.
year: 2003