scholarly journals Capacitance Characteristics and Breakdown Mechanism of AlGaN/GaN Metal–Semiconductor–Metal Varactors and their Anti-Surge Application

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 292
Author(s):  
Chien-Fu Shih ◽  
Yu-Li Hsieh ◽  
Liann-Be Chang ◽  
Ming-Jer Jeng ◽  
Zi-Xin Ding ◽  
...  
Keyword(s):  
Signal Transmission ◽  
Schottky Contact ◽  
Wide Band ◽  
High Electron ◽  
Wide Band Gap ◽  
Breakdown Mechanism ◽  
Metal Semiconductor Metal ◽  
Voltage Dependent ◽  
Protection Circuits ◽  
Surge Protection

The AlGaN/GaN materials with a wide band gap, high electron mobility, and high breakdown voltage are suitable for manufacturing high-power and high-frequency electronic devices. In this study, metal Schottky contact electrodes of different dimensions are prepared on AlGaN/GaN wafers to fabricate metal–semiconductor–metal (MSM) varactors. Voltage-dependent capacitance and breakdown voltages of the varactors are measured and studied. The corresponding breakdown mechanisms of varactors with different electrode gaps are proposed. Furthermore, an anti-surge application using GaN-based MSM varactors in a signal transmission module is demonstrated, and its surge suppression capability is shown. We believe that our study will be beneficial in developing surge protection circuits for RF applications.

The Impact of Non-Ideal Ohmic Contacts on the Performance of High-Voltage SiC MPS Diodes

2019 ◽  
Vol 963 ◽  
pp. 553-557
Author(s):  
Yaren Huang ◽  
Jonas Buettner ◽  
Benedikt Lechner ◽  
Gerhard Wachutka
Keyword(s):  
Ohmic Contact ◽  
Ohmic Contacts ◽  
Schottky Contact ◽  
Wide Band ◽  
Contact Model ◽  
Carrier Injection ◽  
Wide Band Gap ◽  
Tunneling Model ◽  
P Type ◽  
The Impact

The wide band gap of SiC semiconductor devices constitutes a serious challenge to build good Ohmic contacts on the surface of the p-type material. This is reflected in the numerical analysis of ”realistic” devices, where we have to cope with serious problems, such as a shifting threshold voltage, reduced forward conductivity, and no noticeable conductivity modulation by minority carrier injection from p+-emitters, in matching measured data with simulation results, as a consequence of the significant impact of non-ideal poor Ohmic contacts. In this work, we used a Schottky contact model together with a barrier tunneling model, instead of common ideal Ohmic contact model, to simulate the non-ideal Ohmic contact on SiC MPS diodes. Based on this approach, the I-V characteristics of real Ohmic contacts can be reproduced in high-fidelity simulations, providing us physical insight of the observed operational behavior.

ScGaN and ScAlN: emerging nitride materials

2014 ◽  
Vol 2 (17) ◽  
pp. 6042-6050 ◽  
Author(s):  
M. A. Moram ◽  
S. Zhang
Keyword(s):  
Band Gap ◽  
Optoelectronic Devices ◽  
Wide Band ◽  
High Electron Mobility Transistors ◽  
High Electron ◽  
Wide Band Gap ◽  
High Electron Mobility ◽  
Electron Mobility Transistors ◽  
Wide Band Gap Semiconductors ◽  
Energy Harvesting Devices

ScAlN and ScGaN alloys are wide band-gap semiconductors which can greatly expand the options for band gap and polarisation engineering required for efficient III-nitride optoelectronic devices, high-electron mobility transistors and energy-harvesting devices.

High electron doping to a wide band gap semiconductor 12CaO∙7Al2O3 thin film

2007 ◽  
Vol 90 (18) ◽  
pp. 182105 ◽  
Author(s):  
Masashi Miyakawa ◽  
Masahiro Hirano ◽  
Toshio Kamiya ◽  
Hideo Hosono
Keyword(s):  
Thin Film ◽  
Band Gap ◽  
Wide Band ◽  
High Electron ◽  
Wide Band Gap ◽  
Electron Doping

scholarly journals Monolithic Si-Based AlGaN/GaN MIS-HEMTs Comparator and Its High Temperature Characteristics

2021 ◽  
Vol 11 (24) ◽  
pp. 12057
Author(s):  
Fan Li ◽  
Ang Li ◽  
Yuhao Zhu ◽  
Chengmurong Ding ◽  
Yubo Wang ◽  
...  
Keyword(s):  
High Temperature ◽  
Integrated Circuits ◽  
Wide Band ◽  
High Electron Mobility Transistor ◽  
High Electron ◽  
Static Characteristics ◽  
Wide Band Gap ◽  
Mixed Signal Circuits ◽  
Promising Application ◽  
Recessed Gate

Monolithic GaN High Electron Mobility Transistor (HEMT)-integrated circuits are a promising application of wide band-gap materials. To date, most GaN-based devices behave as NMOS-like transistors. As only NMOS GaN HEMT is currently commercially available, its control circuit requires special design if monolithic integration is desired. This article analyzes the schematics of a GaN-based comparator, and three comparator structures are compared through ADS simulation. The optimal structure with the bootstrapped technique is fabricated based on AlGaN/GaN Metal–Insulator–Semiconductor (MIS) HEMT with the recessed gate method. The comparator has excellent static characteristics when the reference voltage increases from 3 V to 8 V. Dynamic waveforms from 10 kHz to 1 MHz are also obtained. High-temperature tests from 25 °C to 250 °C are applied upon both DC and AC characteristics. The mechanisms of instability issues are explained under dynamic working condition. The results prove that the comparator can be used in the state-of-art mixed-signal circuits, demonstrating the potential for the monolithic all-GaN integrated circuits.

scholarly journals ZnO as a Functional Material, a Review

Crystals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 505 ◽  
Author(s):  
Michał A. Borysiewicz
Keyword(s):  
Wide Band ◽  
Future Research ◽  
High Electron ◽  
Functional Material ◽  
Bandgap Engineering ◽  
Wide Band Gap ◽  
Current State ◽  
Main Development ◽  
The Many ◽  
P Type

Zinc oxide (ZnO) is a fascinating wide band gap semiconductor material with many properties that make it widely studied in the material science, physics, chemistry, biochemistry, and solid-state electronics communities. Its transparency, possibility of bandgap engineering, the possibility to dope it into high electron concentrations, or with many transition or rare earth metals, as well as the many structures it can form, all explain the intensive interest and broad applications. This review aims to showcase ZnO as a very versatile material lending itself both to bottom-up and top-down fabrication, with a focus on the many devices it enables, based on epitaxial structures, thin films, thick films, and nanostructures, but also with a significant number of unresolved issues, such as the challenge of efficient p-type doping. The aim of this article is to provide a wide-ranging cross-section of the current state of ZnO structures and technologies, with the main development directions underlined, serving as an introduction, a reference, and an inspiration for future research.

TEM and cathodoluminescence of precipitates in II-VI semiconductors

1988 ◽  
Vol 46 ◽  
pp. 488-489
Author(s):  
Joanna L. Batstone
Keyword(s):  
Crystal Growth ◽  
Band Gap ◽  
Local Strain ◽  
Wide Band ◽  
Optoelectronic Device ◽  
Wide Band Gap ◽  
Bulk Crystal Growth ◽  
Transmission Electron ◽  
Device Applications ◽  
Stoichiometry Control

Interest in II-VI semiconductors centres around optoelectronic device applications. The wide band gap II-VI semiconductors such as ZnS, ZnSe and ZnTe have been used in lasers and electroluminescent displays yielding room temperature blue luminescence. The narrow gap II-VI semiconductors such as CdTe and HgxCd1-x Te are currently used for infrared detectors, where the band gap can be varied continuously by changing the alloy composition x.Two major sources of precipitation can be identified in II-VI materials; (i) dopant introduction leading to local variations in concentration and subsequent precipitation and (ii) Te precipitation in ZnTe, CdTe and HgCdTe due to native point defects which arise from problems associated with stoichiometry control during crystal growth. Precipitation is observed in both bulk crystal growth and epitaxial growth and is frequently associated with segregation and precipitation at dislocations and grain boundaries. Precipitation has been observed using transmission electron microscopy (TEM) which is sensitive to local strain fields around inclusions.

Electron microscopic characterization of diamond thin films and substrates for diamond heteroepitaxial growth

1989 ◽  
Vol 47 ◽  
pp. 592-593
Author(s):  
J.B. Posthill ◽  
R.P. Burns ◽  
R.A. Rudder ◽  
Y.H. Lee ◽  
R.J. Markunas ◽  
...  
Keyword(s):  
Thin Films ◽  
Wide Band ◽  
Deposition Process ◽  
Heteroepitaxial Growth ◽  
Electron Microscopic ◽  
Wide Band Gap ◽  
Lattice Matching ◽  
Different Types ◽  
Diamond Thin Films

Because of diamond’s wide band gap, high thermal conductivity, high breakdown voltage and high radiation resistance, there is a growing interest in developing diamond-based devices for several new and demanding electronic applications. In developing this technology, there are several new challenges to be overcome. Much of our effort has been directed at developing a diamond deposition process that will permit controlled, epitaxial growth. Also, because of cost and size considerations, it is mandatory that a non-native substrate be developed for heteroepitaxial nucleation and growth of diamond thin films. To this end, we are currently investigating the use of Ni single crystals on which different types of epitaxial metals are grown by molecular beam epitaxy (MBE) for lattice matching to diamond as well as surface chemistry modification. This contribution reports briefly on our microscopic observations that are integral to these endeavors.

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