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A Novel Nitrogen Ion Implantation Technique for Turning Thin Film "Normally On" AlGaN/GaN Transistor into "Normally Off" Using TCAD Simulation. MEMBRANES 2021; 11:membranes11110899. [PMID: 34832128 PMCID: PMC8623484 DOI: 10.3390/membranes11110899] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 11/16/2021] [Accepted: 11/19/2021] [Indexed: 11/25/2022]
Abstract
This study presents an innovative, low-cost, mass-manufacturable ion implantation technique for converting thin film normally on AlGaN/GaN devices into normally off ones. Through TCAD (Technology Computer-Aided Design) simulations, we converted a calibrated normally on transistor into a normally off AlGaN/GaN transistor grown on a silicon <111> substrate using a nitrogen ion implantation energy of 300 keV, which shifted the bandgap from below to above the Fermi level. In addition, the threshold voltage (Vth) was adjusted by altering the nitrogen ion implantation dose. The normally off AlGaN/GaN device exhibited a breakdown voltage of 127.4 V at room temperature because of impact ionization, which showed a positive temperature coefficient of 3 × 10−3 K−1. In this study, the normally off AlGaN/GaN device exhibited an average drain current gain of 45.3%, which was confirmed through an analysis of transfer characteristics by changing the gate-to-source ramping. Accordingly, the proposed technique enabled the successful simulation of a 100-µm-wide device that can generate a saturation drain current of 1.4 A/mm at a gate-to-source voltage of 4 V, with a mobility of 1487 cm2V−1s−1. The advantages of the proposed technique are summarized herein in terms of processing and performance.
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An Overview of Normally-Off GaN-Based High Electron Mobility Transistors. MATERIALS 2019; 12:ma12101599. [PMID: 31096689 PMCID: PMC6567103 DOI: 10.3390/ma12101599] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 05/08/2019] [Accepted: 05/14/2019] [Indexed: 11/16/2022]
Abstract
Today, the introduction of wide band gap (WBG) semiconductors in power electronics has become mandatory to improve the energy efficiency of devices and modules and to reduce the overall electric power consumption in the world. Due to its excellent properties, gallium nitride (GaN) and related alloys (e.g., AlxGa1−xN) are promising semiconductors for the next generation of high-power and high-frequency devices. However, there are still several technological concerns hindering the complete exploitation of these materials. As an example, high electron mobility transistors (HEMTs) based on AlGaN/GaN heterostructures are inherently normally-on devices. However, normally-off operation is often desired in many power electronics applications. This review paper will give a brief overview on some scientific and technological aspects related to the current normally-off GaN HEMTs technology. A special focus will be put on the p-GaN gate and on the recessed gate hybrid metal insulator semiconductor high electron mobility transistor (MISHEMT), discussing the role of the metal on the p-GaN gate and of the insulator in the recessed MISHEMT region. Finally, the advantages and disadvantages in the processing and performances of the most common technological solutions for normally-off GaN transistors will be summarized.
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Greco G, Fiorenza P, Iucolano F, Severino A, Giannazzo F, Roccaforte F. Conduction Mechanisms at Interface of AlN/SiN Dielectric Stacks with AlGaN/GaN Heterostructures for Normally-off High Electron Mobility Transistors: Correlating Device Behavior with Nanoscale Interfaces Properties. ACS APPLIED MATERIALS & INTERFACES 2017; 9:35383-35390. [PMID: 28920438 DOI: 10.1021/acsami.7b08935] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In this work, the conduction mechanisms at the interface of AlN/SiN dielectric stacks with AlGaN/GaN heterostructures have been studied combining different macroscopic and nanoscale characterizations on bare materials and devices. The AlN/SiN stacks grown on the recessed region of AlGaN/GaN heterostructures have been used as gate dielectric of hybrid metal-insulator-semiconductor high electron mobility transistors (MISHEMTs), showing a normally-off behavior (Vth = +1.2 V), high channel mobility (204 cm2 V-1 s-1), and very good switching behavior (ION/IOFF current ratio of (5-6) × 108 and subthreshold swing of 90 mV/dec). However, the transistors were found to suffer from a positive shift of the threshold voltage during subsequent bias sweeps, which indicates electron trapping in the dielectric stack. To get a complete understanding of the conduction mechanisms and of the charge trapping phenomena in AlN/SiN films, nanoscale current and capacitance measurements by conductive atomic force microscopy (C-AFM) and scanning capacitance microscopy (SCM) have been compared with a macroscopic temperature-dependent characterization of gate current in MIS capacitors. The nanoscale electrical analyses showed the presence of a spatially uniform distribution of electrons trapping states in the insulator and the occurrence of a density of 7 × 108 cm-2 of local and isolated current spots at high bias values. These nanoscale conductive paths can be associated with electrically active defects responsible for the trap-assisted current transport mechanism through the dielectric, observed by the temperature-dependent characterization of the gate current. The results of this study can be relevant for future applications of AlN/SiN bilayers in GaN hybrid MISHEMT technology.
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Affiliation(s)
- Giuseppe Greco
- Consiglio Nazionale delle Ricerche-Istituto per la Microelettronica e Microsistemi (CNR-IMM) , Strada VIII, No. 5, Zona Industriale, 95121 Catania, Italy
| | - Patrick Fiorenza
- Consiglio Nazionale delle Ricerche-Istituto per la Microelettronica e Microsistemi (CNR-IMM) , Strada VIII, No. 5, Zona Industriale, 95121 Catania, Italy
| | | | - Andrea Severino
- STMicroelectronics , Stradale Primosole 50, 95121 Catania, Italy
| | - Filippo Giannazzo
- Consiglio Nazionale delle Ricerche-Istituto per la Microelettronica e Microsistemi (CNR-IMM) , Strada VIII, No. 5, Zona Industriale, 95121 Catania, Italy
| | - Fabrizio Roccaforte
- Consiglio Nazionale delle Ricerche-Istituto per la Microelettronica e Microsistemi (CNR-IMM) , Strada VIII, No. 5, Zona Industriale, 95121 Catania, Italy
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Sang L, Zhu QS, Yang SY, Liu GP, Li HJ, Wei HY, Jiao CM, Liu SM, Wang ZG, Zhou XW, Mao W, Hao Y, Shen B. Band offsets of non-polar A-plane GaN/AlN and AlN/GaN heterostructures measured by X-ray photoemission spectroscopy. NANOSCALE RESEARCH LETTERS 2014; 9:470. [PMID: 25258600 PMCID: PMC4167304 DOI: 10.1186/1556-276x-9-470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Accepted: 08/26/2014] [Indexed: 06/03/2023]
Abstract
The band offsets of non-polar A-plane GaN/AlN and AlN/GaN heterojunctions are measured by X-ray photoemission spectroscopy. A large forward-backward asymmetry is observed in the non-polar GaN/AlN and AlN/GaN heterojunctions. The valence-band offsets in the non-polar A-plane GaN/AlN and AlN/GaN heterojunctions are determined to be 1.33 ± 0.16 and 0.73 ± 0.16 eV, respectively. The large valence-band offset difference of 0.6 eV between the non-polar GaN/AlN and AlN/GaN heterojunctions is considered to be due to piezoelectric strain effect in the non-polar heterojunction overlayers.
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Affiliation(s)
- Ling Sang
- State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Qin Sheng Zhu
- Key Laboratory of Semiconductor Material Science, Beijing Key Laboratory of Low Dimensional Semiconductor Materials and Devices, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Shao Yan Yang
- Key Laboratory of Semiconductor Material Science, Beijing Key Laboratory of Low Dimensional Semiconductor Materials and Devices, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Gui Peng Liu
- Key Laboratory of Semiconductor Material Science, Beijing Key Laboratory of Low Dimensional Semiconductor Materials and Devices, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Hui Jie Li
- Key Laboratory of Semiconductor Material Science, Beijing Key Laboratory of Low Dimensional Semiconductor Materials and Devices, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Hong Yuan Wei
- Key Laboratory of Semiconductor Material Science, Beijing Key Laboratory of Low Dimensional Semiconductor Materials and Devices, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Chun Mei Jiao
- Key Laboratory of Semiconductor Material Science, Beijing Key Laboratory of Low Dimensional Semiconductor Materials and Devices, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Shu Man Liu
- Key Laboratory of Semiconductor Material Science, Beijing Key Laboratory of Low Dimensional Semiconductor Materials and Devices, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Zhan Guo Wang
- Key Laboratory of Semiconductor Material Science, Beijing Key Laboratory of Low Dimensional Semiconductor Materials and Devices, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Xiao Wei Zhou
- State Key Discipline Laboratory of Wide Band Gap Semiconductor Technology, Xidian University, Xi’an 710071, China
| | - Wei Mao
- State Key Discipline Laboratory of Wide Band Gap Semiconductor Technology, Xidian University, Xi’an 710071, China
| | - Yue Hao
- State Key Discipline Laboratory of Wide Band Gap Semiconductor Technology, Xidian University, Xi’an 710071, China
| | - Bo Shen
- State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
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Fontserè A, Pérez-Tomás A, Placidi M, Llobet J, Baron N, Chenot S, Cordier Y, Moreno JC, Jennings MR, Gammon PM, Fisher CA, Iglesias V, Porti M, Bayerl A, Lanza M, Nafría M. Nanoscale investigation of AlGaN/GaN-on-Si high electron mobility transistors. NANOTECHNOLOGY 2012; 23:395204. [PMID: 22971927 DOI: 10.1088/0957-4484/23/39/395204] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
AlGaN/GaN HEMTs are devices which are strongly influenced by surface properties such as donor states, roughness or any kind of inhomogeneity. The electron gas is only a few nanometers away from the surface and the transistor forward and reverse currents are considerably affected by any variation of surface property within the atomic scale. Consequently, we have used the technique known as conductive AFM (CAFM) to perform electrical characterization at the nanoscale. The AlGaN/GaN HEMT ohmic (drain and source) and Schottky (gate) contacts were investigated by the CAFM technique. The estimated area of these highly conductive pillars (each of them of approximately 20-50 nm radius) represents around 5% of the total contact area. Analogously, the reverse leakage of the gate Schottky contact at the nanoscale seems to correlate somehow with the topography of the narrow AlGaN barrier regions producing larger currents.
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Affiliation(s)
- A Fontserè
- IMB-CNM-CSIC, Campus UAB, 08193 Bellaterra, Barcelona, Spain.
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