scholarly journals Extreme electron polaron spatial delocalization in π-conjugated materials

2015 ◽  
Vol 112 (45) ◽  
pp. 13779-13783 ◽  
Author(s):  
Jeff Rawson ◽  
Paul J. Angiolillo ◽  
Michael J. Therien
Keyword(s):  
Performance Metrics ◽  
Electronic Device ◽  
Conjugated Materials ◽  
Light Emitting ◽  
Spin Resonance ◽  
Spatial Dimensions ◽  
Device Applications ◽  
Charge Transfer Reactions ◽  
Reorganization Energies ◽  
Electron Reduction

The electron polaron, a spin-1/2 excitation, is the fundamental negative charge carrier in π-conjugated organic materials. Large polaron spatial dimensions result from weak electron-lattice coupling and thus identify materials with unusually low barriers for the charge transfer reactions that are central to electronic device applications. Here we demonstrate electron polarons in π-conjugated multiporphyrin arrays that feature vast areal delocalization. This finding is evidenced by concurrent optical and electron spin resonance measurements, coupled with electronic structure calculations that suggest atypically small reorganization energies for one-electron reduction of these materials. Because the electron polaron dimension can be linked to key performance metrics in organic photovoltaics, light-emitting diodes, and a host of other devices, these findings identify conjugated materials with exceptional optical, electronic, and spintronic properties.

A Critical Comparison Between Movpe and MBE Growth of III-V Nitride Semiconductor Materials for Opto-Electronic Device Applications

1998 ◽  
Vol 537 ◽  
Author(s):  
M.A.L. Johnson ◽  
Zhonghai Yu ◽  
J.D. Brown ◽  
F.A. Koeck ◽  
N.A. El-Masry ◽  
...  
Keyword(s):  
Electronic Device ◽  
Light Emitting Diode ◽  
Rf Plasma ◽  
Nitrogen Species ◽  
Active Nitrogen ◽  
Mbe Growth ◽  
Light Emitting ◽  
Device Applications ◽  
Materials Used ◽  
P Type

AbstractA systematic study of the growth and doping of GaN, AlGaN, and InGaN by both molecular beam epitaxy (MBE) and metal-organic vapor phase epitaxy (MOVPE) has been performed. Critical differences between the resulting epitaxy are observed in the p-type doping using magnesium as the acceptor species. MBE growth, using rf-plasma sources to generate the active nitrogen species for growth, has been used for III-Nitride compounds doped either n-type with silicon or p-type with magnesium. Blue and violet light emitting diode (LED) test structures were fabricated. These vertical devices required a relatively high forward current and exhibited high leakage currents. This behavior was attributed to parallel shorting mechanisms along the dislocations in MBE grown layers. For comparison, similar devices were fabricated using a single wafer vertical flow MOVPE reactor and ammonia as the active nitrogen species. MOVPE grown blue LEDs exhibited excellent forward device characteristics and a high reverse breakdown voltage. We feel that the excess hydrogen, which is present on the GaN surface due to the dissociation of ammonia in MOVPE, acts to passivate the dislocations and eliminate parallel shorting for vertical device structures. These findings support the widespread acceptance of MOVPE, rather than MBE, as the epitaxial growth technique of choice for III-V nitride materials used in vertical transport bipolar devices for optoelectronic applications.

Blue like Diamond Light Emitting Devices to be Massproduced

1989 ◽  
Vol 162 ◽  
Author(s):  
M. Kadono ◽  
S. Hayashi ◽  
N. Hirose ◽  
K. Itoh ◽  
T. Inushima ◽  
...  
Keyword(s):  
Thin Films ◽  
Electronic Device ◽  
Electronic Devices ◽  
Chemical Properties ◽  
Wide Band ◽  
Wide Band Gap ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Device Applications ◽  
Diamond Thin Films

Recently, there has been considerable interest in electronic device applications of diamond thin films. The chemical properties of diamond is stable. So diamond thin films become very useful if they are used for electronic devices. We consider diamond thin films as blue like emitting devices because diamond has a wide band gap(about 5.5eV). Some light emitting devices have been known [1]. First of all we have been trying to deposit diamond thin films on the large areas. If they deposit on the large areas, light emitting devices may be massproduced.

scholarly journals A Critical Comparison Between MOVPE and MBE Growth of III-V Nitride Semiconductor Materials for Opto-Electronic Device Applications

1999 ◽  
Vol 4 (S1) ◽  
pp. 594-599 ◽  
Author(s):  
M.A.L. Johnson ◽  
Zhonghai Yu ◽  
J.D. Brown ◽  
F.A. Koeck ◽  
N.A. El-Masry ◽  
...  
Keyword(s):  
Electronic Device ◽  
Light Emitting Diode ◽  
Rf Plasma ◽  
Nitrogen Species ◽  
Active Nitrogen ◽  
Mbe Growth ◽  
Light Emitting ◽  
Device Applications ◽  
Materials Used ◽  
P Type

A systematic study of the growth and doping of GaN, AlGaN, and InGaN by both molecular beam epitaxy (MBE) and metal-organic vapor phase epitaxy (MOVPE) has been performed. Critical differences between the resulting epitaxy are observed in the p-type doping using magnesium as the acceptor species. MBE growth, using rf-plasma sources to generate the active nitrogen species for growth, has been used for III-Nitride compounds doped either n-type with silicon or p-type with magnesium. Blue and violet light emitting diode (LED) test structures were fabricated. These vertical devices required a relatively high forward current and exhibited high leakage currents. This behavior was attributed to parallel shorting mechanisms along the dislocations in MBE grown layers. For comparison, similar devices were fabricated using a single wafer vertical flow MOVPE reactor and ammonia as the active nitrogen species. MOVPE grown blue LEDs exhibited excellent forward device characteristics and a high reverse breakdown voltage. We feel that the excess hydrogen, which is present on the GaN surface due to the dissociation of ammonia in MOVPE, acts to passivate the dislocations and eliminate parallel shorting for vertical device structures. These findings support the widespread acceptance of MOVPE, rather than MBE, as the epitaxial growth technique of choice for III-V nitride materials used in vertical transport bipolar devices for optoelectronic applications.

scholarly journals Topological electronics

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Matthew J. Gilbert
Keyword(s):  
Information Processing ◽  
Physical Properties ◽  
Materials Science ◽  
Electronic Device ◽  
Condensed Matter ◽  
Topological Phases ◽  
Applied Physics ◽  
New Paradigm ◽  
Topological Materials ◽  
Device Applications

AbstractWithin the broad and deep field of topological materials, there are an ever-increasing number of materials that harbor topological phases. While condensed matter physics continues to probe the exotic physical properties resulting from the existence of topological phases in new materials, there exists a suite of “well-known” topological materials in which the physical properties are well-characterized, such as Bi2Se3 and Bi2Te3. In this context, it is then appropriate to ask if the unique properties of well-explored topological materials may have a role to play in applications that form the basis of a new paradigm in information processing devices and architectures. To accomplish such a transition from physical novelty to application based material, the potential of topological materials must be disseminated beyond the reach of condensed matter to engender interest in diverse areas such as: electrical engineering, materials science, and applied physics. Accordingly, in this review, we assess the state of current electronic device applications and contemplate the future prospects of topological materials from an applied perspective. More specifically, we will review the application of topological materials to the general areas of electronic and magnetic device technologies with the goal of elucidating the potential utility of well-characterized topological materials in future information processing applications.

scholarly journals Methylamines as Nitrogen Precursors in Chemical Vapor Deposition of Gallium Nitride

2018 ◽  
Author(s):  
Karl Rönnby ◽  
Sydney C. Buttera ◽  
Polla Rouf ◽  
Sean Barry ◽  
Lars Ojamäe ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Surface Chemistry ◽  
Gas Phase ◽  
Vapor Deposition ◽  
Electronic Device ◽  
Chemical Vapor ◽  
Group 13 ◽  
Gas Phase Chemistry ◽  
Device Applications ◽  
Phase Chemistry

Chemical vapor deposition (CVD) is one of the most important techniques for depositing thin films of the group 13 nitrides (13-Ns), AlN, GaN, InN and their alloys, for electronic device applications. The standard CVD chemistry for 13-Ns use ammonia as the nitrogen precursor, however, this gives an inefficient CVD chemistry forcing N/13 ratios of 100/1 or more. Here we investigate the hypothesis that replacing the N-H bonds in ammonia with weaker N-C bonds in methylamines will permit better CVD chemistry, allowing lower CVD temperatures and an improved N/13 ratio. Quantum chemical computations shows that while the methylamines have a more reactive gas phase chemistry, ammonia has a more reactive surface chemistry. CVD experiments using methylamines failed to deposit a continuous film, instead micrometer sized gallium droplets were deposited. This study shows that the nitrogen surface chemistry is most likely more important to consider than the gas phase chemistry when searching for better nitrogen precursors for 13-N CVD.

scholarly journals Methylamines as Nitrogen Precursors in Chemical Vapor Deposition of Gallium Nitride

2019 ◽  
Author(s):  
Karl Rönnby ◽  
Sydney C. Buttera ◽  
Polla Rouf ◽  
Sean Barry ◽  
Lars Ojamäe ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Surface Chemistry ◽  
Gas Phase ◽  
Vapor Deposition ◽  
Electronic Device ◽  
Chemical Vapor ◽  
Group 13 ◽  
Gas Phase Chemistry ◽  
Device Applications ◽  
Phase Chemistry

Chemical vapor deposition (CVD) is one of the most important techniques for depositing thin films of the group 13 nitrides (13-Ns), AlN, GaN, InN and their alloys, for electronic device applications. The standard CVD chemistry for 13-Ns use ammonia as the nitrogen precursor, however, this gives an inefficient CVD chemistry forcing N/13 ratios of 100/1 or more. Here we investigate the hypothesis that replacing the N-H bonds in ammonia with weaker N-C bonds in methylamines will permit better CVD chemistry, allowing lower CVD temperatures and an improved N/13 ratio. Quantum chemical computations shows that while the methylamines have a more reactive gas phase chemistry, ammonia has a more reactive surface chemistry. CVD experiments using methylamines failed to deposit a continuous film, instead micrometer sized gallium droplets were deposited. This study shows that the nitrogen surface chemistry is most likely more important to consider than the gas phase chemistry when searching for better nitrogen precursors for 13-N CVD.

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