Effect of Externally-Imposed Radial Strain on the Piezoelectric Response of MOCVD-Grown Gallium Nitride

2000 ◽  
Vol 639 ◽  
Author(s):  
Jennifer A. Himes ◽  
James R. Willis ◽  
Daniel A. Gulino
Keyword(s):  
Gallium Nitride ◽  
Radial Stress ◽  
Contact Point ◽  
Electrical Contact ◽  
Radial Strain ◽  
Wide Band ◽  
Piezoelectric Response ◽  
Mocvd Reactor ◽  
Ionic Systems ◽  
Film Substrate

ABSTRACTThe large piezoelectric constants of GaN suggest possible application of GaN-based materials in piezoelectric sensors, among other areas. GaN's wide band gap implies that these sensors will fare well over a broad temperature range and/or in a harsh environment.In this work, films of gallium nitride approximately 0.75 micron thick and grown by MOCVD were subject to an externally-imposed radial stress condition. Deposition was performed in a commercial MOCVD reactor (CVD, Inc.) at 1323K using trimethylgallium and ammonia as the chemical precursors. The substrate was one-inch diameter silicon (111). After deposition, titanium dots were deposited in various locations, including the wafer center, by evaporation. Stress was applied to the film/substrate system using a modified micrometer head (Mitutoyo) mounted to an Ionic Systems Basic Stressgauge (model 30285). Stress levels were calculated based on the magnitude of the imposed deflection as read from the micrometer head display, and the piezoelectric response at any particular dot with respect to the center dot was measured by measuring the voltage difference using a digital multimeter (Keithley 175). The micrometer head impinged on the center dot and served as one electrical contact point.Effective piezoelectric coefficients were measured as a function of imposed radial stress. Applied stresses in the range of 1 to 5 GPa resulted in effective piezoelectric coefficients ranging from –0.6 to –2.0 × 10-5 C/m2

Two-dimensional wide band-gap nitride semiconductor GaN and AlN materials：properties, fabrication and applications

2021 ◽  
Author(s):  
Zhongxin Wang ◽  
Guodong Wang ◽  
Xintong Liu ◽  
Shouzhi Wang ◽  
Tailin Wang ◽  
...  
Keyword(s):  
Gallium Nitride ◽  
Band Gap ◽  
Hot Spot ◽  
Wide Band ◽  
Aluminium Nitride ◽  
Semiconductor Materials ◽  
Two Dimensional ◽  
Wide Band Gap ◽  
Nitride Semiconductor ◽  
New Generation

Gallium nitride (GaN) and aluminium nitride (AlN), as the representatives of new generation of wide band gap semiconductor materials, have become a hot spot in the semiconductor field due to...

scholarly journals Analytical validation of the Young–Dupré law for epitaxially-strained thin films

2019 ◽  
Vol 29 (12) ◽  
pp. 2183-2223 ◽  
Author(s):  
Elisa Davoli ◽  
Paolo Piovano
Keyword(s):  
Thin Films ◽  
Contact Point ◽  
Variational Model ◽  
Analytical Validation ◽  
Regularity Of Minimizers ◽  
Transmission Problems ◽  
Thin Film Model ◽  
New Ideas ◽  
Film Substrate ◽  
Regularity Results

We present here an analysis of the regularity of minimizers of a variational model for epitaxially strained thin-films. The regularity of energetically-optimal film profiles is studied by extending previous methods and by developing new ideas based on transmission problems. The achieved regularity results relate to both the Stranski-Krastanow and the Volmer-Weber modes, the possibility of different elastic properties between the film and the substrate, and the presence of the surface tensions of all three involved interfaces: film/gas, substrate/gas, and film/substrate. Finally, geometrical conditions are provided for the optimal wetting angle, i.e. the angle formed at the contact point of films with the substrate. In particular, the Young–Dupré law is shown to hold, yielding what appears to be the first analytical validation of such law for a thin-film model in the context of Continuum Mechanics.

The Effect of Carrier Gas and Reactor Pressure on Gallium Nitride Growth in MOCVD Manufacturing Process

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Omar Jumaah ◽  
Yogesh Jaluria
Keyword(s):  
Thin Films ◽  
Growth Rate ◽  
Gallium Nitride ◽  
Chemical Vapor ◽  
Wide Band ◽  
Rotating Disk ◽  
Organic Chemical ◽  
Gas Mixture ◽  
Carrier Gas ◽  
Reactor Pressure

Gallium nitride (GaN) is an attractive material for manufacturing light emitting diodes and other electronic devices due to its wide band-gap and superb optoelectronic performance. The quality of GaN thin film determines the reliability and durability of these devices. Metal-organic chemical vapor deposition (MOCVD) is a common technique used to fabricate high-quality GaN thin films. In this paper, GaN growth rate and uniformity in a vertical rotating disk MOCVD reactor are investigated on the basis of a three-dimensional computational fluid dynamics (CFD) model. GaN growth rate is investigated under the influence of reactor pressure, precursor concentration ratio, and composition of the carrier gas mixture. The numerical simulation shows that the carrier gas mixture and the reactor pressure have significant effects on growth rate and uniformity of GaN thin films. It is also found that an appropriate mixture of N2 and H2 may be employed as the carrier gas to improve the flow field characteristic in the reactor. This results in an improved crystal growth of GaN thin films.

Increase in the piezoelectric response of scandium-doped gallium nitride thin films sputtered using a metal interlayer for piezo MEMS

2019 ◽  
Vol 114 (1) ◽  
pp. 012902 ◽  
Author(s):  
Masato Uehara ◽  
Takaaki Mizuno ◽  
Yasuhiro Aida ◽  
Hiroshi Yamada ◽  
Keiichi Umeda ◽  
...  
Keyword(s):  
Thin Films ◽  
Gallium Nitride ◽  
Piezoelectric Response

A Study of MOCVD-Grown Gallium Nitride Nucleation Layers on Sapphire

1992 ◽  
Vol 280 ◽  
Author(s):  
A. Estes Wickenden ◽  
D. K. Wickenden ◽  
T. J. Kistenmacher ◽  
S. A. Ecelberger ◽  
T. O. Poehler
Keyword(s):  
Gallium Nitride ◽  
Sapphire Substrate ◽  
Low Temperatures ◽  
Carrier Gas ◽  
Mocvd Reactor ◽  
Nucleation Sites

ABSTRACTNucleation layers of GaN have been deposited in an MOCVD reactor on (0001) sapphire, over a range of temperatures and layer thicknesses, using either N2 or H2 carrier gas. The layers have been found to be continuous, textured films as deposited at low temperatures (600°C), but to reorder upon annealing, segregating into nucleation sites which exhibit the normal heteroepitaxial relationship with the sapphire substrate.

Ion Beam Enhanced Adhesion

1983 ◽  
Vol 25 ◽  
Author(s):  
T. A. Tombrello
Keyword(s):  
Electronic Excitation ◽  
Ion Beam ◽  
Electrical Contact ◽  
Exothermic Reaction ◽  
Metal Films ◽  
Metal Coatings ◽  
Dose Threshold ◽  
Tape Test ◽  
Polymeric Substrates ◽  
Film Substrate

ABSTRACTWe have shown that the irradiation of a wide variety of thin film-substrate combinations with MeV/amu ions leads to greatly enhanced adhesion. The systems studied include metal films on dielectric, semiconductor, and metal substrates. For metal coatings on semiconductors the electrical contact which is originally diode-like becomes ohmic. Metal films on metal or polymeric substrates generally require the lowest dose irradiations. For Au on Ta the threshold dose to achieve a constant level of adhesion (“Scotch Tape” test) is consistent with a model of the process in which the dose threshold varies with the electronic excitation part of the energy loss in the material as (dE/dx + Q)−2 . The value of Q obtained corresponds to an exothermic reaction due to the increased binding that liberates ˜70 eV at the interface. This model and a variant of it based on the production of K-shell vacancies in low Z elements in the target will be discussed.

Package Design and Analysis for Vertical Gallium Nitride Field Effect Transistors

2021 ◽  
Vol 2021 (HiTEC) ◽  
pp. 000058-000063
Author(s):  
John Harris ◽  
David Huitink ◽  
Dan Ewing
Keyword(s):  
Gallium Nitride ◽  
High Temperature ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Wide Band ◽  
Development Stage ◽  
Wide Band Gap ◽  
Package Design ◽  
Bulk Gan ◽  
Effect Transistor

Abstract Gallium nitride (GaN) is a wide band gap semi-conductor with superior electron mobility to silicon carbide. These properties allow for the design of high temperature capable devices with excellent on resistance and breakdown voltage for their size. However, bulk GaN is difficult to fabricate and doping for field effect transistor (FET) control has been elusive, so vertical GaN devices are not commonplace. This paper measures the characteristics of vertical GaN FETs in the development stage and discusses packaging them for fabrication feedback and for future high temperature aplications.

Cathodoluminescence, Photoluminescence, and Optical Absorbance Spectroscopy of Aluminum Gallium Nitride (AlxGa1−xN) Films

1998 ◽  
Vol 13 (9) ◽  
pp. 2480-2497 ◽  
Author(s):  
Lawrence H. Robins ◽  
Jeremiah R. Lowney ◽  
Dennis K. Wickenden
Keyword(s):  
Gallium Nitride ◽  
Aluminum Gallium Nitride ◽  
Deep Level ◽  
Chemical Vapor ◽  
Band Edge ◽  
Structural Defects ◽  
Excitation Mode ◽  
Optical Absorbance ◽  
Pl Spectra ◽  
Film Substrate

Aluminum gallium nitride (AlxGa1−xN) films, grown by metalorganic chemical vapor deposition on sapphire, were characterized by low-temperature cathodoluminescence (CL) and photoluminescence (PL), and room-temperature optical absorbance. The aluminum fractions are estimated to range from x = 0 to x = 0.444. Most films were silicon-doped. The absorption spectra have a Urbach (exponential) form below the bandgap. The width of the Urbach edge, EU, increases with Al fraction, x, as EU = (0.045 +1 0.104x) eV. The luminescence (CL or PL) spectra show a relatively narrow band-edge peak and a broad deep-level peak. The full-widths at half-maximum of the band-edge CL peaks (measured at T = 15 K) are remarkably similar to the Urbach absorption widths, EU (measured at T = 300 K). PL spectra were obtained from the top surfaces and the film-substrate interfaces of several films. The interface PL spectra of some films show an extra peak 0.15 eV to 0.45 eV below the bandgap, which is ascribed to structural defects or impurity phases localized near the interface. The energy of the band-edge luminescence peak shifts with excitation mode (CL, top-surface PL, or interface PL). This effect is attributed to the variation of the excitation depth, between the top surface and film-substrate interface, with excitation mode, together with the depth variation of film properties such as residual stress or aluminum fraction.

Solid-state lighting with wide band gap semiconductors

2014 ◽  
Vol 1 ◽  
Author(s):  
Faiz Rahman
Keyword(s):  
Gallium Nitride ◽  
Solid State ◽  
Band Gap ◽  
Light Emitting Diodes ◽  
Rapid Development ◽  
Wide Band ◽  
Solid State Lighting ◽  
Wide Band Gap ◽  
Light Emitting ◽  
Wide Band Gap Semiconductors

ABSTRACTLight-emitting diodes (LEDs) made from wide band gap semiconductors, such as gallium nitride, are undergoing rapid development. Solid-state lighting with these LEDs is transforming patterns of energy usage and lifestyle throughout the world.With solid-state lighting gradually taking over from incandescent and fluorescent lighting, light-emitting diodes (LEDs) are very much the focus of research nowadays. This compact review takes a look at LEDs for lighting applications made from wide band gap semiconductors. A very brief history of electric lighting is included for completeness, followed by a description of blue-emitting LEDs that serve as pump sources for all ‘white’ LEDs. This is followed by a discussion on techniques to extract more light from the confines of LED chips through surface patterning. The thermal management of LEDs is perhaps the most important consideration in designing and using LED-based luminaires. This topic is discussed with regard to recent studies on LED reliability. The very promising development of gallium nitride-on-silicon LEDs is examined next followed by a discussion on phosphors for color conversion in LEDs. LED lighting has positively influenced both upscale and downscale illumination markets worldwide. Its societal impact is examined, with the review concluding with a look at efforts to produce LEDs from zinc oxide – a material that holds much promise for the future of solid-state lighting.

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