Article
Engineering, Electrical & Electronic
Caixia Hou, Rodrigo M. Gazoni, Roger J. Reeves, Martin W. Allen
Summary: This study reports a significant improvement in the rectifying performance of Pd Schottky contacts on β-Ga2O3 at high temperatures in air, leading to similar thermal characteristics as diamond and SiC contacts at 500 degrees C. The increase in rectifying performance is attributed to the oxidation of the Pd SC layer, creating higher barrier height PdO regions that dominate high-temperature current transport. Additionally, good agreement was observed between the temperature dependence of the built-in voltage of the thermally oxidized Pd SCs and the optical bandgap of β-Ga2O3.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Review
Physics, Applied
Chao Lu, Xueqiang Ji, Zeng Liu, Xu Yan, Nianpeng Lu, Peigang Li, Weihua Tang
Summary: This review summarizes recent research progress on beta-Ga2O3-metal contacts, including related theories, measurements, fabrication processes, and control methods. These studies provide important insights for both theoretical understanding of the metal/semiconductor interface and the fabrication process for engineering applications of Ga2O3-based devices.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2022)
Article
Multidisciplinary Sciences
Manuele Bettelli, Silvia Zanettini, Leonardo Abbene, Francesca Casoli, Lucia Nasi, Giovanna Trevisi, Fabio Principato, Antonino Buttacavoli, Andrea Zappettini
Summary: With the rise of the 4th Generation Synchrotron Light Sources and other applications, there is a strong need for direct X-ray detection under high photon flux. The novel Cadmium Zinc Telluride (CZT) developed by Redlen Technologies is considered a reference material for such applications. This study reports a detailed investigation on the characteristics of new optimized sputtered platinum electrical contacts on HF-CZT detectors.
SCIENTIFIC REPORTS
(2023)
Article
Materials Science, Coatings & Films
Luke A. M. Lyle, Kunyao Jiang, Elizabeth V. Favela, Kalyan Das, Andreas Popp, Zbigniew Galazka, Guenter Wagner, Lisa M. Porter
Summary: The Schottky barriers of Ti, Mo, Co, Ni, Pd, and Au on (100) beta-Ga2O3 substrates were analyzed using a combination of J-V, C-V, and J-V-T measurements. The results revealed a strong positive correlation between the calculated Schottky barrier heights and the metal work functions.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2021)
Review
Engineering, Electrical & Electronic
Hardhyan Sheoran, Vikram Kumar, Rajendra Singh
Summary: This study comprehensively reviews the recent development of metal-semiconductor contacts on ultrawide bandgap beta-gallium oxide (beta-Ga2O3). The study starts by introducing the basic concepts of metal-semiconductor contacts and then summarizes the current literature on ohmic and Schottky contacts on beta-Ga2O3. Finally, the status of high-power Schottky diode contact on beta-Ga2O3 is presented.
ACS APPLIED ELECTRONIC MATERIALS
(2022)
Article
Engineering, Electrical & Electronic
Elizabeth Favela, Kun Zhang, Matthew J. Cabral, Alice Ho, Sun Ho Kim, Kalyan K. Das, Lisa M. Porter
Summary: We investigated the thermal stability of Co/Au and Ni/Au Schottky contacts on Sn-doped beta-Ga2O3 substrates. The SBHs of the contacts remained largely constant during annealing at 300 degrees C, but degraded after extended annealing at 500 degrees C. Characterizations revealed changes in film morphology, interdiffusion, and phase segregation within the contacts after annealing at 500 degrees C. Co/Au or Ni/Au Schottky contacts have potential for use in Ga2O3 devices at temperatures below 300 degrees C.
JOURNAL OF ELECTRONIC MATERIALS
(2023)
Article
Nanoscience & Nanotechnology
Palvan Seyidov, Joel B. Varley, Ymir Kalmann Frodason, Detlef Klimm, Lasse Vines, Zbigniew Galazka, Ta-Shun Chou, Andreas Popp, Klaus Irmscher, Andreas Fiedler
Summary: The thermal stability of different Schottky contacts (Au, Pt, and Ni) on (100) beta-Ga2O3 single crystals grown by the Czochralski method is investigated. The contact-dependent defect levels and behavior changes during temperature cycling were observed.
ADVANCED ELECTRONIC MATERIALS
(2023)
Article
Physics, Applied
Fabien C-P. Massabuau, Francesca Adams, David Nicol, John C. Jarman, Martin Frentrup, Joseph W. Roberts, Thomas J. O'Hanlon, Andras Kovacs, Paul R. Chalker, R. A. Oliver
Summary: The structural, chemical and electrical properties of Ni/Au contacts to alpha-Ga2O3 were studied. Ni forms a Schottky contact with alpha-Ga2O3 regardless of the post-annealing temperature. No metal oxidation was observed at the metal-semiconductor interface, and the electrical properties were dominated by the Ni-Au bilayer metallurgical processes. 400-450 degrees C was found to be the optimal annealing temperature, allowing for metal diffusion to heal gaps at the metal/semiconductor interface without significant interdiffusion and alloy formation between Ni and Au.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Engineering, Electrical & Electronic
Mihee Ji, Neil R. Taylor, Ivan Kravchenko, Pooran Joshi, Tolga Aytug, Lei R. Cao, M. Parans Paranthaman
Summary: This study demonstrated large-size vertical beta-Ga2O3 Schottky barrier diodes on a Si-doped n-type drift layer grown on a bulk Sn-doped beta-Ga2O3 substrate, with various device areas showing different breakdown voltages and ideality factors while maintaining relatively low specific on-state resistance.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2021)
Article
Chemistry, Analytical
Shiyu Zhang, Zeng Liu, Yuanyuan Liu, Yusong Zhi, Peigang Li, Zhenping Wu, Weihua Tang
Summary: In this work, an SBD based on EFG Ga2O3 crystal substrate is fabricated and characterized. Electrical parameters such as Ron, φB, n, Rs, and Nd are extracted systematically by analyzing J-V and C-V curves of the device. The detailed measurements and theoretical analysis are presented in this paper.
Article
Engineering, Electrical & Electronic
Sosorburam Boldbaatar, V. Janardhanam, Munkhsaikhan Zumuukhorol, Hoon-Ki Lee, Hae-Yong Lee, Hyo Jung Kim, Kyu-Hwan Shim, Chel-Jong Choi
Summary: We investigated Ni Schottky contacts on alpha-Ga2O3 epitaxial layers and studied their current-voltage characteristics at temperatures ranging from 100 to 425 K. The Ni/alpha-Ga2O3 Schottky diode showed excellent rectification with a high barrier height of 1.39 eV, a low leakage current of around 10-12 A, and a breakdown voltage of 215 V at room temperature. The temperature dependence of the barrier height and ideality factor indicated the presence of barrier inhomogeneity at the Schottky interface, with a transition occurring at 250 K.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2023)
Article
Chemistry, Physical
Qihao Zhang, Jiangwei Liu, Chunming Tu, Dongyuan Zhai, Min He, Jiwu Lu
Summary: High-performance beta-Ga2O3-based Schottky barrier diodes (SBDs) and metal-semiconductor field-effect transistors (MESFETs) were fabricated on a highly doped epitaxial wafer. The electrical properties and stabilities of these devices after annealing were investigated. The results showed excellent ON/OFF ratios for all SBDs, and the MESFETs exhibited pinch-off and saturation characteristics with high drain currents, surpassing previous reports. The study provides valuable insights for the development of practical applications of beta-Ga2O3-based electronic devices.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Chemistry, Multidisciplinary
Yanxiao Sun, Luyue Jiang, Zhe Wang, Zhenfei Hou, Liyan Dai, Yankun Wang, Jinyan Zhao, Ya-Hong Xie, Libo Zhao, Zhuangde Jiang, Wei Ren, Gang Niu
Summary: In this work, MoS2 photodetectors with nanoscale channel length and back-gate device structure were demonstrated. The devices showed high responsivity of 4.1 x 103 A W-1 and detectivity of 1.34 x 1013 cm Hz1/2 W-1 at 650 nm. They were also sensitive to multiwavelength lights, including 520 and 405 nm.
Article
Engineering, Electrical & Electronic
Saurav Roy, Arkka Bhattacharyya, Carl Peterson, Sriram Krishnamoorthy
Summary: In this study, a lateral beta-Ga2O3 Schottky barrier diode with a high-k dielectric superjunction structure is demonstrated. The proposed structure addresses the challenges of achieving charge balance in beta-Ga2O3 using conventional p-n superjunction structures, and also allows for reduced on-resistance and high breakdown voltage. Experimental results show the great potential of beta-Ga2O3 in multi-kilovolt class applications.
IEEE ELECTRON DEVICE LETTERS
(2022)
Article
Engineering, Electrical & Electronic
Yuxi Wei, Xiaorong Luo, Yuangang Wang, Juan Lu, Zhuolin Jiang, Jie Wei, Yuanjie Lv, Zhihong Feng
Summary: This study proposes an ultrafast reverse recovery beta-Ga2O3 Schottky barrier diode with improved breakdown voltage, featuring a compound termination design. The compound termination effectively reduces reverse leakage current, enhances reverse recovery and breakdown characteristics, showing great potential for high power and high-frequency applications.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2021)
Article
Physics, Applied
C. Hou, K. R. York, R. A. Makin, S. M. Durbin, R. M. Gazoni, R. J. Reeves, M. W. Allen
APPLIED PHYSICS LETTERS
(2020)
Article
Engineering, Electrical & Electronic
Krystal R. York, Robert A. Makin, Nancy Senabulya, James P. Mathis, Roy Clarke, Roger J. Reeves, Steven M. Durbin
Summary: The research successfully grew high-quality MgSnN2 thin films on yttria-stabilized zirconia substrates by adjusting the growth parameters, and controlled disorder in the cation sublattice, enabling continuous tuning of the band gap values.
JOURNAL OF ELECTRONIC MATERIALS
(2021)
Article
Chemistry, Physical
Alexandra R. McNeill, Rodrigo Martinez-Gazoni, Roger J. Reeves, Martin W. Allen, Alison J. Downard
Summary: ZnO is a strong candidate for transparent electronic devices due to its wide band gap and earth-abundance, but its practical use is limited by surface metallicity. Modification of ZnO single crystal surfaces with aryl films and NP films can decrease the downward surface band bending, with evidence of Zn-O-C bonding provided by XPS measurements.
Article
Engineering, Electrical & Electronic
Caixia Hou, Rodrigo M. Gazoni, Roger J. Reeves, Martin W. Allen
Summary: This study reports a significant improvement in the rectifying performance of Pd Schottky contacts on β-Ga2O3 at high temperatures in air, leading to similar thermal characteristics as diamond and SiC contacts at 500 degrees C. The increase in rectifying performance is attributed to the oxidation of the Pd SC layer, creating higher barrier height PdO regions that dominate high-temperature current transport. Additionally, good agreement was observed between the temperature dependence of the built-in voltage of the thermally oxidized Pd SCs and the optical bandgap of β-Ga2O3.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Physics, Applied
Chikezie C. Onyema, Roger J. Reeves, Martin W. Allen
Summary: MESFETs were fabricated on ZnO thin films grown via mist-CVD, using in situ intentionally oxidized AgOx SC gates to achieve high performance. These devices showed potential for producing low-cost, low operating voltage, transparent thin film transistors due to the significant increase in Schottky barrier height and passivation of oxygen vacancies at the gate-channel interface.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Chemistry, Physical
Rodrigo F. Martinez-Gazoni, Martin W. Allen, Roger J. Reeves
Summary: The study investigated the persistent photoconductivity (PPC) of high-quality SnO2 (101) films grown by molecular beam epitaxy (MBE), showing that the longest duration was achieved under high-vacuum conditions, sensitivity to pressure changes, and the dominant role of water vapor. Increasing carrier concentration significantly increased the duration, while decreasing temperature led to a significant decrease in persistent photoconductivity.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Physics, Applied
Z. Dela Cruz, C. Hou, R. F. Martinez-Gazoni, R. J. Reeves, M. W. Allen
Summary: The performance of beta-Ga2O3 Schottky contacts (SCs) fabricated using amorphous, intentionally oxidized platinum-iridium alloys was investigated. The study found that Pt0.5Ir0.5Ox SCs had the highest Schottky barriers on all beta-Ga2O3 crystal faces, providing better contacts and lower reverse leakage currents. All PtyIr(1-y)Ox SCs on ( 2 over bar 01) beta-Ga2O3 showed excellent high-temperature performance.
APPLIED PHYSICS LETTERS
(2022)
Article
Engineering, Electrical & Electronic
Liam R. Carroll, Rodrigo F. Martinez-Gazoni, Nicola Gaston, Roger J. Reeves, Alison J. Downard, Martin W. Allen
Summary: The study investigates the covalent modification of beta-Ga2O3 surfaces with organic layers to control their surface band bending. The research shows that NP modification leads to upward band bending shifts while ODPA modification results in downward shifts in surface band bending. These findings provide valuable insights for the electronic applications of beta-Ga2O3.
ACS APPLIED ELECTRONIC MATERIALS
(2021)
Article
Materials Science, Multidisciplinary
R. A. Makin, K. R. York, A. S. Messecar, S. M. Durbin
