Download or read book The Effects of Thermal Strain and Neutron Irradiation on Defect Formation in AlGaN GaN High Electron Mobility Transistors and GaN Schottky Diodes written by Chung-Han Lin and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Our DRCLS, SPS, time-resolved SPS (t-SPS), current-voltage-temperature (I-V-T) shows that fast and thermal neutron preferentially affect device properties. Fast neutron will induce defects in GaN by recoil and displacement damage whereas thermal neutron tends to enhance the interaction between metal/semiconductor interfaces due to heat. Time-resolved surface photovoltage spectroscopy (t-SPS) results reveal a defect evolution of GaN under fast neutron irradiation that indicates low fast neutron dosage will enhance GaN properties a result which is confirmed by DRCLS results. XPS results show that Ti and Ni are more resistant than other metal but will interact with GaN at higher thermal neutron fluence. Our results show that fast and thermal neutrons are both detrimental electronic devices without proper protection.
Download or read book The Role of Defects on Schottky and Ohmic Contact Characteristics for GaN and AlGaN GaN High electron Mobility Transistors written by Dennis Eugene Walker and published by . This book was released on 2006 with total page 217 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: The AlGaN/GaN material system is ideally suited for UV detectors, light sources, and high performance, high power transistors. Through an understanding of the physics and device properties associated with defects, engineered solutions can allow the utilization of the full potential of AlGaN/GaN device properties. Auger Electron Spectroscopy (AES) and secondary electron threshold (SET) techniques allow the characterization of band bending and work function at semiconductor surfaces. Using these techniques with ultra-high vacuum (UHV) sample cleaving and metal deposition, Schottky barrier formation to non-polar GaN was investigated revealing cases of both ideal band-bending and Fermi level pinning. Cathodoluminescence spectroscopy (CL) allows the investigation of luminescent defect levels with depth-resolving capability by controlling the incident beam voltage and associated electron beam penetration into the sample. High electron mobility transistors (HEMTs) exhibiting current collapse were investigated using CL and CL mapping and specific defects were found in the GaN channel and buffer regions that may help explain the current collapse phenomena. Coupling a novel gate mask into a typical HEMT fabrication sequence and utilizing three, independent UHV sample cleaning techniques including thermal desorption of contaminants, Ga-reflux, and N2 ion sputtering, and metallization of the gates on AlGaN/GaN HEMTs, correlations in defect levels, surface cleaning technique, and finished device performance were found. In analyzing the CL data for this sample, however, a specific feature located just below the GaN near band edge was observed to accumulate near the Ohmic contacts prompting a further investigation of both the effects of the RIE etch used in producing the UHV-compatible mask as well as four different Ohmic contact structures on both defect levels determined by CL and on final device performance. Finally, a bulk GaN sample was processed with Ohmic contacts to determine the correlation of the AlGaN device layer in the formation of this defect level associated with the Ohmic contacts and the role of the mesa RIE etch on the same defect. Through these investigations, progress in the underlying physics of Schottky barrier formation on GaN and the important role of defects on device performance using AES, SET, and CL have been demonstrated.
Download or read book Impact of Electrically and Thermally Induced Physical Defects on the Reliability of AlGaN GaN High Electron Mobility Transistors written by Monta Raymond Holzworth (Jr) and published by . This book was released on 2013 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt: AlGaN/GaN high electron mobility transistors are unique for their combination of high temperature, high power, and high frequency applications. Compared to Si, Ge, and compound semiconductors such as GaAS and InP, AlGaN/GaN transistors outclass the current technology due to their superior combination of high breakdown voltage and high frequency performance. These characteristics arise from structural and electrical properties inherent to the AlGaN/GaN heterojunction which have enabled AlGaN/GaN transistors usage in important military and civilian applications such as microwave and millimeter technology, RADAR systems, and as high current and voltage switches in utility grid systems. As the technology continues to improve due to increased materials quality and device advancements, future applications will require AlGaN/GaN transistor usage under even higher voltages and temperatures. Therefore, the effects of these stresses need to be investigated in order improve device performance and reliability.
Download or read book Temperature Dependent Current voltage Measurements of Neutron Irradiated A10 27Ga0 73N GaN Modulation Doped Field Effect Transistors written by Troy A. Uhlman and published by . This book was released on 2005 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Reliability limiting Defects in GaN A1GaN High Electron Mobility Transistors written by Tania Roy and published by . This book was released on 2011 with total page 101 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Impact of Gamma irradiation on the Characteristics of III N GaN Based High Electron Mobility Transistors written by Anupama Yadav and published by . This book was released on 2016 with total page 107 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study, the fundamental properties of AlGaN/GaN based High Electron Mobility Transistors (HEMTs) have been investigated in order to optimize their performance in radiation harsh environment. AlGaN/GaN HEMTs were irradiated with 60Co gamma-rays to doses up to 1000 Gy, and the effects of irradiation on the devices' transport and optical properties was analyzed. Understanding the radiation affects in HEMTs devices, on carrier transport, recombination rates and traps creation play a significant role in development and design of radiation resistant semiconductor components for different applications.
Download or read book Chemical Abstracts written by and published by . This book was released on 2002 with total page 2002 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effects of 2 MeV Ge Irradiation on AlGaN GaN High Electron Mobility Transistors written by and published by . This book was released on 2012 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Surface and Mechanical Stress Effects in AlGaN GaN High Electron Mobility Transistors written by Sameer Jayanta Joglekar and published by . This book was released on 2017 with total page 161 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gallium Nitride (GaN) belongs to a class of materials called wide band-gap semiconductors. In recent years, the versatile nature of this material has been exploited for a wide range of applications from solid state lighting to RF and microwave communication, as well as high power switching. The first part of this thesis discusses planar AlGaN/GaN transistors. GaN is a piezoelectric material, and changes in mechanical stress result in a change in the charge density which in turn affects the maximum current in AlGaN/GaN transistors. Finite element modelling techniques were applied to quantify the mechanical stress distribution in planar AlGaN/GaN RF transistors resulting from device fabrication, and operation in the on- and off-state. Thereafter, two important surface and interface effects were studied in this thesis. In the first one, the impact of surface cleanings, surface treatments and plasma-based dry etch conditions on two different types of ohmic contact technologies was investigated. Contact resistance measurements were correlated with surface characterization results. The second was that of interface positive charges at the Al2O3-GaN interface and the increase in electron density in the device resulting from them. In both these problems, a combination of device electrical measurements and material characterization techniques was used to establish direct correlations between device behavior and material properties. The second part of the thesis deals exclusively with nano-ribbon (NR) or fin-like AlGaN/GaN transistors. Fundamental transport properties of charge density and mobility in NR devices were studied in order to understand the difference in behavior of these devices from planar devices. The influence of passivation films on the charge density in these structures was investigated, using Al2O3 passivation as a specific example. Electron mobility degradation due to sidewall-scattering in NR devices was quantified using different mobility extraction methods based on device measurements. The thesis concludes with a potential application of NR AlGaN/GaN transistors for high linearity power amplification. A new kind of transistor with varying threshold voltages along the gate width is proposed to improve the DC and RF linearity of GaN-based devices.
Download or read book Current Collapse Induced in AlGaN GaN High Electron Mobility Transistors by Bias Stress written by and published by . This book was released on 2003 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: Current collapse is observed to be induced in AlGaN/GaN high-electron-mobility transistors as a result of short-term bias stress. This effect was seen in devices grown by both metalorganic chemical vapor deposition (MOCVD) and molecular-beam epitaxy (MBE). The induced collapse appears to be permanent and can be reversed by SiN passivation. The traps responsible for the collapse have been studied by photoionization spectroscopy. For the MOCVD-grown devices, the same traps cause the collapse in both unstressed and stressed devices. These effects are thought to result from hot-carrier damage during stress.
Download or read book Quantitative Defect Spectroscopy on Operating AlGaN GaN High Electron Mobility Transistors written by Andrew C Malonis and published by . This book was released on 2009 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Despite numerous advances in the growth, fabrication, and characterization of AlGaN/GaN HEMT devices, there remain a number of unknowns related to the impact of deep levels on HEMT performance. Of specific interest to ongoing development of HEMT technology is the development of techniques which can not only detect the specific energy levels of deep levels in operating devices, but can also relate the presence of these defects to changes in specific device parameters. By examining more established techniques and developing new on-device characterization methods, the impact of defects on AlGaN/GaN HEMTs was quantitatively studied.
Download or read book ReliabilityStudy Of Power Gallium Nitride Transistors written by and published by Marcon Denis. This book was released on with total page 229 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigation of Electrically Active Defects in GaN AlGaN and AlGaN GaN High Electron Mobility Transistors written by Aaron R. Arehart and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: To further refine the capabilities to quantitativelymeasure defect energies and concentrations in the access regions of HEMTs, an atomic forcemicroscope is adapted to perform nanometer-scale defect characterization. Using scanning Kelvin probe microscopy, evidence of the spatial and time-dependent measurement capabilities is demonstrated. Initial HEMT results are presented and suggest the total trap concentration of ~1012 cm−2 consistent with previous results.
Download or read book Degradation Mechanisms of GaN HEMTs written by Jungwoo Joh and published by . This book was released on 2007 with total page 85 pages. Available in PDF, EPUB and Kindle. Book excerpt: (Cont.) From a set of our experiments, we have hypothesized that the main mechanism behind device degradation is defect formation through the inverse piezoelectric effect and subsequent electron trapping. Unlike current conventional wisdom, hot electrons are less likely to be the direct cause of electrical degradation in the devices that we have studied. Our studies suggest a number of possibilities to improve the electrical reliability of GaN HEMTs.
Download or read book Radiation Response and Reliability of AlGaN GaN HEMTs written by Jin Chen and published by . This book was released on 2013 with total page 69 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Reliability written by and published by . This book was released on 2012 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Effect of Radiation on the Electrical Properties of Aluminum Gallium Nitride Gallium Nitride Heterostructures written by John W. McClory and published by . This book was released on 2008 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: AlGaN/GaN Heterojunction Field Effect Transistors (HFETs) were irradiated at low temperature and the temperature dependent changes to drain current, gate current, capacitance, and transconductance were measured. The results were compared to the charge control model of the drain current and trap-assisted tunneling model of the gate current to determine the source of the radiation-induced changes. AlGaN/GaN HFETs demonstrated threshold voltage shifts and drain current changes after irradiation. After electron and neutron irradiation applied at ~80 K, measurement of the drain current at this temperature showed an increase that saturated after 10^13 electrons/cm^2 or 10^10 neutrons/cm^2 due to positive charge build-up in the AlGaN layer. Measurement at room temperature after low-temperature irradiation showed a decrease in drain current due to the build up of charged defects along the AlGaN-GaN interface that decrease the mobility in the 2DEG and hence decrease the current. Gate leakage currents increased after low temperature irradiation and the increase was persistent after room temperature annealing. The increased leakage current was attributed to trap-assisted tunneling after application of the trap-assisted tunneling model. Comparison of the model to post-irradiation vs. pre-irradiation data showed that the dominant parameter change causing increased gate current was an increase in trap concentration.
