Author: Rong JiangPublisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages :
Book Description
Bias Dependence of Radiation Response and Reliability of AlGaN/GaN HEMTs
Author: Rong JiangPublisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages :
Book Description
Radiation Response and Reliability of AlGaN/GaN HEMTs
Author: Jin ChenPublisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 69
Book Description
Radiation Response and Reliability of High Speed AlGaN/GaN HEMTs
Author: Jin ChenPublisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 95
Book Description
Investigation of Electrical Bias, Mechanical Stress, Temperature and Ambient Effect on AlGaN/GaN Hemt Time-Dependent Degradation
Author: Amit GuptaPublisher:
ISBN:
Category :
Languages : en
Pages : 143
Book Description
AlGaN/GaN HEMT technology is promising for RF and high power applications. However commercial usability of this technology is currently hindered because of its limited electrical reliability which still remains a major concern. AlGaN/GaN HEMTs have been shown to degrade irreversibly under typical device operation and there is widespread disagreement on the underlying fundamental physics for the observed device degradation. Electrical degradation in AlGaN/GaN HEMTs due to DC stressing is studied typically by performing electrical step stress tests and a critical voltage is determined. Device degradation is characterized by changes measured in electrical parameters, such as increase in Rs and RD, decrease in IDsat, decrease in gm, Vt shift and sub-threshold change. The widely accepted theory attributes such degradation to the inverse piezoelectric effect. Electric field due to applied bias generates biaxial tensile stress which together with intrinsic stress from lattice mismatch increases the elastic energy of AlGaN layer.
AlGaN/GaN HEMTs Reliability
Author: Ponky IvoPublisher: Cuvillier Verlag
ISBN: 3736942591
Category : Technology & Engineering
Languages : en
Pages : 132
Book Description
AlGaN/GaN HEMTs reliability and stability issues were investigated in dependence on epitaxial design and process modification. DC-Step-Stress-Tests have been performed on wafers as a fast device robustness screening method. As a criterion of robustness they deliver a critical source-drain voltage for the onset of degradation. Several degradation modes were observed which depend on epi design, epi quality and process technology. Electrical and optical characterizations together with electric field simulations were performed to get insight into respective degradation modes. It has been found that AlGaN/GaN HEMT devices with GaN cap show higher critical source-drain voltages as compared to non-capped devices. Devices with low Al concentration in the AlGaN barrier layer also show higher critical source-drain voltages. Superior stability and robustness performance have been achieved from devices with AlGaN backbarrier epi design grown on n-type SiC substrate. For the onset on any degradation modes the presence of high electrical fields is most decisive for ON- and OFF-state operation conditions. Therefore careful epi design to reduce high electric field is mandatory. It is also shown that epi buffer quality and growth process have a great impact on device robustness. Defects such as point defects and dislocations are assumed to be created initially during stressing and accumulated to larger defect clusters during device stressing. Electroluminescence (EL) measurements were performed to detect early degradation. Extended localized defects are resulting as bright spots at OFF-state conditions in conjunction with a gate leakage increase. AlGaN/GaN HEMTs mit unterschiedlichen epitaktischen Designs und Prozessmodifikationen wurden auf ihre Zuverlässigkeit und Stabilität untersucht. DC-Stufenstresstests wurden als Screeningmethode für die Bauelementrobustheit durchgeführt. Mit dieser Methode erhält man eine kritische Source-Drain-Spannung, die den Beginn der Degradation kennzeichnet. Verschiedene Degradationsmodi wurden beobachtet, die vom epitaxialem Design, der epitaxialen Qualität und der Prozesstechnologie abhängen. Elektrische und optische Messungen zusammen mit elektrischen Feldsimulationen wurden durchgeführt, um Einblick in das Degradationsverhalten zu bekommen. Es hat sich gezeigt, dass AlGaN/GaN HEMTs mit einer GaN Cap-Schicht eine höhere kritische Drain-Source-Spannung zeigen als Transistoren ohne diese Schicht. HEMTs mit niedriger Aluminiumkonzentration in der AlGaN-Barriere zeigen ebenfalls eine höhere kritische Drain-Source-Spannung. Transistoren mit AlGaNBackbarrier, die auf n-Typ SiC-Substraten gewachsen wurden, zeigen eine besonders hohe Stabilität und Robustheit. Für den Betrieb im ON-State als auch im OFF-State ist ein hohes elektrisches Feld entscheidend für den Beginn der Degradation. Daher sind epitaxiale Designs, die das elektrische Feld so weit wie möglich reduzieren, von großer Wichtigkeit. Es wird gezeigt, dass die Qualität der Bufferschicht und der Wachstumsprozess der epitaxierten Schichten großen Einfluß auf die Robustheit der Bauelemente haben. Zu Beginn des Stressprozesses werden Punktdefekte und Versetzungen erzeugt, die im weiteren Verlauf des Stresstests zu Agglomeration von Defektclustern führen. Der Beginn der Degradation wurde mit Hilfe der Elektrolumineszenz untersucht. Im OFF-State werden ausgedehnte lokalisierte Defekte als stark leuchtende Flecken detektiert, wobei gleichzeitig ein Anstieg der Leckströme zu beobachten ist.
Noise in Nanoscale Semiconductor Devices
Author: Tibor GrasserPublisher: Springer Nature
ISBN: 3030375005
Category : Technology & Engineering
Languages : en
Pages : 724
Book Description
This book summarizes the state-of-the-art, regarding noise in nanometer semiconductor devices. Readers will benefit from this leading-edge research, aimed at increasing reliability based on physical microscopic models. Authors discuss the most recent developments in the understanding of point defects, e.g. via ab initio calculations or intricate measurements, which have paved the way to more physics-based noise models which are applicable to a wider range of materials and features, e.g. III-V materials, 2D materials, and multi-state defects. Describes the state-of-the-art, regarding noise in nanometer semiconductor devices; Enables readers to design more reliable semiconductor devices; Offers the most up-to-date information on point defects, based on physical microscopic models.
Trapping Effects in AlGaN/GaN HEMTs for High Frequency Applications
Author: Chieh Kai YangPublisher:
ISBN:
Category :
Languages : en
Pages : 109
Book Description
Abstract: Any defect site existing in the AlGaN/GaN HEMTs can be electrically active during device operation. The activated defect site not only could lead to a degradation in the output characteristics but may introduce additional nonlinearity which seriously downgrades the values of devices for various applications. This motivates us to study the detailed path experimentally and theoretically how an electrically-activated defect site could impact the device performances during practical device operation. In this study, the g oal is (1) to give device engineers ideas on how further improvements can be devised to strengthen the existing GaN technology and (2) to provide circuit designers with better understanding on how to use GaN devices more efficiently for the development of reliable commercial GaN products for higher power applications in wireless systems. Single tone characterization results of AlGaN/GaN HEMTs for Class A operation are presented and compared. A new combined large signal network analyzer / deep level optical spectroscopy system is utilized to study the impact of illumination on the CW large-signal load line and small-signal S-parameters variations to identify the possible energy level of the trapping center responsible for the degradation of the device performance. A new pulsed-IV pulsed-RF "coldFET" technique is introduced to extract parasitic elements existing in the access regions of AlGaN/GaN HEMTs. The observation of bias-dependence is detailed and a simple semi-physical model is proposed which provides a satisfactory description of experimental results. The low-frequency noise, an important figure of merit in terms of reliability, is briefly-reviewed. Additive phase noise measurements are presented and the effects of illumination and load impedance are examined. A physical expression is derived and simulated which successfully establishes a relationship between the access resistance and the low-frequency noise and provides a qualitative description of the measurement results.
Power GaN Devices
Author: Matteo MeneghiniPublisher: Springer
ISBN: 3319431994
Category : Technology & Engineering
Languages : en
Pages : 383
Book Description
This book presents the first comprehensive overview of the properties and fabrication methods of GaN-based power transistors, with contributions from the most active research groups in the field. It describes how gallium nitride has emerged as an excellent material for the fabrication of power transistors; thanks to the high energy gap, high breakdown field, and saturation velocity of GaN, these devices can reach breakdown voltages beyond the kV range, and very high switching frequencies, thus being suitable for application in power conversion systems. Based on GaN, switching-mode power converters with efficiency in excess of 99 % have been already demonstrated, thus clearing the way for massive adoption of GaN transistors in the power conversion market. This is expected to have important advantages at both the environmental and economic level, since power conversion losses account for 10 % of global electricity consumption. The first part of the book describes the properties and advantages of gallium nitride compared to conventional semiconductor materials. The second part of the book describes the techniques used for device fabrication, and the methods for GaN-on-Silicon mass production. Specific attention is paid to the three most advanced device structures: lateral transistors, vertical power devices, and nanowire-based HEMTs. Other relevant topics covered by the book are the strategies for normally-off operation, and the problems related to device reliability. The last chapter reviews the switching characteristics of GaN HEMTs based on a systems level approach. This book is a unique reference for people working in the materials, device and power electronics fields; it provides interdisciplinary information on material growth, device fabrication, reliability issues and circuit-level switching investigation.
Dependence of Power and Efficiency of A1GaN/GaN HEMT's on the Load Resistance for Class B Bias
Author: V. KaperPublisher:
ISBN:
Category :
Languages : en
Pages : 8
Book Description
The material properties of GaN and the AlGaN/GaN heterostructure such as high breakdown field and high sheet charge density, allow AlGaN/GaN HEMTs to be operated at significantly higher drain bias voltages as compared to other Ill-V compound semiconductor FETs 1. As expected, larger RF voltage and current swings result in higher nonnalized output power at microwave frequencies. AlGaN/GaN HEMT's are capable of generating output power density in excess of 10W/mm 2, 3 in X-band, which is at least an order of magnitude larger than what is obtainable with GaAs FETs. In this paper, we will discuss the effect of the load impedance on measured output power (Pout) and efficiency (eta) at various drain bias conditions in Class B mode. Dynamic loadlines extracted at the device's output are used for analysis of the trade-off between voltage and current swings at different load resistances and its effect on output power and efficiency.
Author: