On electrical analysis of Al-rich p-AlGaN films for III-nitride UV light emitters

2021 ◽  
Author(s):  
Aakash Jadhav ◽  
Pegah Bagheri ◽  
Andrew Klump ◽  
Dolar Khachariya ◽  
Seiji Mita ◽  
...  
Keyword(s):  
Ionization Energy ◽  
Ohmic Contacts ◽  
Uv Light ◽  
Hole Concentration ◽  
Large Area ◽  
Light Emitters ◽  
Alternative Scheme ◽  
Free Hole ◽  
Current Voltage ◽  
Order Of Magnitude

Abstract In this work, an alternative scheme to estimate the resistivity and ionization energy of Al-rich p-AlGaN epitaxial films is developed using two large-area ohmic contacts. Accordingly, the resistivities measured using current-voltage measurements were observed to corroborate the Hall measurements in the Van der Pauw configuration. A free hole concentration of ~1.5 x 1017 cm-3 and low ionization energy of ~65 meV in Mg-doped Al0.7Ga0.3N films is demonstrated. Nearly an order of magnitude lower hydrogen concentration than Mg in the as-grown AlGaN films is thought to reduce the Mg passivation and enable higher hole concentrations in Al-rich p-AlGaN films, compared to p-GaN films. The alternate methodology proposed in this work is expected to provide a simpler pathway to evaluate the electrical characteristics of Al-rich p-AlGaN films for future III-nitride ultraviolet light emitters.

Short period p-type AlN/AlGaN superlattices for deep UV light emitters

2009 ◽  
Vol 1202 ◽  
Author(s):  
Sergey A. Nikishin ◽  
Boris Borisov ◽  
Vladimir Mansurov ◽  
Mahesh Pandikunta ◽  
Indra Chary ◽  
...  
Keyword(s):  
Ohmic Contacts ◽  
Uv Light ◽  
Hole Concentration ◽  
Specific Contact Resistance ◽  
Light Emitters ◽  
Short Period ◽  
Specific Contact ◽  
Short Period Superlattices ◽  
Deep Uv ◽  
P Type

AbstractThe Mg doped AlN/AlxGa1-xN (0.03 ≤ x ≤ 0.05) short period superlattices (SPSLs) were grown by gas source molecular beam epitaxy on (0001) sapphire substrates. The average AlN mole fraction is ∼ 0.7 and the hole concentration is ∼ 7×1017 cm-3. Contacts formed to the SPSLs using Ni/Au bilayer are found to have specific contact resistance ∼ 5×10-5 Ωcm2 near room temperature and to show weak temperature dependence attributed to activation of Mg acceptors in the AlN barriers of SPSLs. These p-SPSLs are attractive for fabrication of transparent low resistive ohmic contacts for deep UV LEDs.

Growth, Characterization, and Application of High Al-content AlGaN and High Power III-Nitride Ultraviolet Emitters

2004 ◽  
Vol 831 ◽  
Author(s):  
Z. Ren ◽  
S.-R. Jeon ◽  
M. Gherasimova ◽  
G. Cui ◽  
J. Han ◽  
...  
Keyword(s):  
Electrical Transport ◽  
Uv Light ◽  
Pulse Mode ◽  
Structural Defects ◽  
Growth Surface ◽  
Large Area ◽  
Minimum Concentration ◽  
Free Hole ◽  
Al Content ◽  
Growth Characterization

ABSTRACTA study of Si-doped and Mg-doped AlxGa1-xN up to × ∼ 50 % and the characteristics of ultraviolet (UV) light emitting diodes (LEDs) with emission wavelengths at 340 nm and 290 nm are reported. By using grading super-lattices (SLs) before n-type AlGaN growth, surface roughness is much improved. Resistivity of 2.9×10-2 Ωcm and free electron concentrations of 2.9×10 cm- are achieved for n-type Al0.45Ga0.55N. The viability of effective p-type doping is defined by a minimum concentration of Mg required to offset the background impurities and, more importantly, a maximum limit above which inversion domains and structural defects start to nucleate, accompanied by a rapid degradation of electrical transport. Resistivity of 10 Ωcm and free hole concentrations above 1017 cm−3 are achieved for AlxGa1-xN up to × ∼ 50 % within an optimum window of Mg incorporation. Output powers up to 1.5 mW from small area 340 nm LEDs (< 100 μm diameter) and 110 μW from 290 nm LEDs (100 μm diameter) directly off a planar chip have been achieved under DC condition. For large area encapsulated lamp (1×1 mm2 device area and 0.52 mm2 mesa area), output power of 79 mW from 340 nm LEDs and 8.5 mW from 290 nm LEDs are achieved under pulse mode (1kHz, 2% duty factor).

TEM Studies and Contact Resistance of Au/Ni/Ti/Ta/n-GaN Ohmic Contacts

2003 ◽  
Vol 764 ◽  
Author(s):  
D.N. Zakharov ◽  
Z. Liliental-Weber ◽  
A. Motayed ◽  
S.N. Mohammad
Keyword(s):  
Contact Resistance ◽  
Ohmic Contacts ◽  
High Resolution Electron Microscopy ◽  
X Ray ◽  
Electron Energy Loss Spectrometry ◽  
Resolution Electron ◽  
Order Of Magnitude ◽  
Contact Surfaces ◽  
Electron Energy Loss ◽  
Magnitude Difference

AbstractOhmic Ta/Ti/Ni/Au contacts to n-GaN have been studied using high resolution electron microscopy (HREM), energy dispersive X-ray spectrometry (EDX) and electron energy loss spectrometry (EELS). Two different samples were used: A - annealed at 7500C withcontact resistance 5×10-6 Ω cm2 and B-annealed at 7750C with contact resistance 6×10-5 Ω cm2. Both samples revealed extensive in- and out-diffusion between deposited layers with some consumption ofGaNlayerand formation of TixTa1-xN50 (0<x<25) at the GaN interface. Almost an order of magnitude difference in contact resistances can be attributed to structure and chemical bonding of Ti-O layers formed on the contact surfaces.

scholarly journals Magneto-optical design of anomalous Nernst thermopile

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jian Wang ◽  
Asuka Miura ◽  
Rajkumar Modak ◽  
Yukiko K. Takahashi ◽  
Ken-ichi Uchida
Keyword(s):  
Optical Design ◽  
Polarized Light ◽  
Ferromagnetic Material ◽  
Light Polarization ◽  
Optical Recording ◽  
Induced Voltage ◽  
Large Area ◽  
Circularly Polarized Light ◽  
Out Of Plane ◽  
Order Of Magnitude

AbstractThe introduction of spin caloritronics into thermoelectric conversion has paved a new path for versatile energy harvesting and heat sensing technologies. In particular, thermoelectric generation based on the anomalous Nernst effect (ANE) is an appealing approach as it shows considerable potential to realize efficient, large-area, and flexible use of heat energy. To make ANE applications viable, not only the improvement of thermoelectric performance but also the simplification of device structures is essential. Here, we demonstrate the construction of an anomalous Nernst thermopile with a substantially enhanced thermoelectric output and simple structure comprising a single ferromagnetic material. These improvements are achieved by combining the ANE with the magneto-optical recording technique called all-optical helicity-dependent switching of magnetization. Our thermopile consists only of Co/Pt multilayer wires arranged in a zigzag configuration, which simplifies microfabrication processes. When the out-of-plane magnetization of the neighboring wires is reversed alternately by local illumination with circularly polarized light, the ANE-induced voltage in the thermopile shows an order of magnitude enhancement, confirming the concept of a magneto-optically designed anomalous Nernst thermopile. The sign of the enhanced ANE-induced voltage can be controlled reversibly by changing the light polarization. The engineering concept demonstrated here promotes effective utilization of the characteristics of the ANE and will contribute to realizing its thermoelectric applications.

scholarly journals The Effects of Amorphous Layer Regrowth on Carbon Activation in GaAs and InP

1993 ◽  
Vol 316 ◽  
Author(s):  
A.J. Moll ◽  
J.W. Ager ◽  
K.M. Yu ◽  
W. Walukiewicz ◽  
E.E. Haller
Keyword(s):  
Hole Concentration ◽  
Amorphous Layer ◽  
Free Hole ◽  
Initial Results

ABSTRACTThe effect of the Ga dose on the activation of implanted carbon in GaAs is determined. The free hole concentration is found to depend on the depth of the amorphous layer created by the Ga co-implant. Initial results on C implantation in InP indicate the behavior of C is very different in InP when compared to GaAs. The role of precipitation in reducing the activation of C in both GaAs and InP is discussed.

An effective and efficient approach to p-type AlN by Be2:O codoping from first-principles calculations

2016 ◽  
Vol 30 (20) ◽  
pp. 1650257
Author(s):  
Meng Zhao ◽  
Wenjun Wang ◽  
Jun Wang ◽  
Junwei Yang ◽  
Weijie Hu ◽  
...  
Keyword(s):  
First Principles ◽  
Ionization Energy ◽  
Hole Concentration ◽  
Valence Band Maximum ◽  
First Principles Calculations ◽  
Mutual Compensation ◽  
Efficient Approach ◽  
P Type ◽  
Codoping Method

Various Be:O-codoped AlN crystals have been investigated via first-principles calculations to evaluate the role of the different combinations in effectively and efficiently inducing p-type carriers. It is found that the O atom is favored to bond with two Be atoms. The formed Be2:O complexes decrease the acceptor ionization energy to 0.11 eV, which is 0.16 eV lower than that of an isolated Be in AlN, implying that the hole concentration could probably be increased by 2–3 orders of magnitude. The electronic structure of Be2:O-codoped AlN shows that the lower ionization energy can be attributed to the interaction between Be and O. The Be–O complexes, despite failing to induce p-type carriers for the mutual compensation of Be and O, introduce new occupied states on the valence-band maximum (VBM) and hence the energy needed for the transition of electrons to the acceptor level is reduced. Thus, the Be2:O codoping method is expected to be an effective and efficient approach to realizing p-type AlN.

Effect of deep-level states on current-voltage characteristics and electroluminescence of blue and UV light-emitting diodes

2010 ◽  
Vol 207 (6) ◽  
pp. 1489-1496 ◽  
Author(s):  
R. Nana ◽  
P. Gnanachchelvi ◽  
M. A. Awaah ◽  
M. H. Gowda ◽  
A. M. Kamto ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Deep Level ◽  
Uv Light ◽  
Light Emitting ◽  
Current Voltage ◽  
Current Voltage Characteristics

scholarly journals Large-area printing of ferroelectric surface and super-domains for efficient solar water splitting

2020 ◽  
Author(s):  
Yu Tian ◽  
Yaqing Wei ◽  
Minghui Pei ◽  
Rongrong Cao ◽  
Zhenao Gu ◽  
...  
Keyword(s):  
Water Splitting ◽  
Electric Fields ◽  
Electronic Structures ◽  
Active Sites ◽  
Large Area ◽  
Solar Water Splitting ◽  
High Efficient ◽  
Catalytic Sites ◽  
Order Of Magnitude ◽  
Magnitude Increase

Abstract Surface electronic structures of the photoelectrodes determine the activity and efficiency of the photoelectrochemical water splitting, but the controls of their surface structures and interfacial chemical reactions remain challenging. Here, we use ferroelectric BiFeO3 as a model system to demonstrate an efficient and controllable water splitting reaction by large-area constructing the hydroxyls-bonded surface. The up-shift of band edge positions at this surface enables and enhances the interfacial holes and electrons transfer through the hydroxyl-active-sites, leading to simultaneously enhanced oxygen and hydrogen evolutions. Furthermore, printing of ferroelectric super-domains with microscale checkboard up/down electric fields separates the distribution of reduction/oxidation catalytic sites, enhancing the charge separation and giving rise to an order of magnitude increase of the photocurrent. This large-area printable ferroelectric surface and super-domains offer an alternative platform for controllable and high-efficient photocatalysis.

scholarly journals Methods for measuring the local emission characteristics of CNT based multi-tip emitters

2021 ◽  
Vol 2103 (1) ◽  
pp. 012116
Author(s):  
E O Popov ◽  
A G Kolosko ◽  
S V Filippov ◽  
S A Ponyaev
Keyword(s):  
Enhancement Factor ◽  
Field Enhancement ◽  
Emission Characteristics ◽  
Large Area ◽  
Software Complex ◽  
Emission Area ◽  
Current Voltage ◽  
Local Emission ◽  
Current Voltage Characteristics ◽  
Comparison Of The Results

Abstract The work is aimed at obtaining microscopic emission characteristics of individual emission sites of a multi-tip field cathode or large-area emitter (LAFE) based on processing the current-voltage characteristics and emission glow patterns. Processing was carried out on a hardware-software complex for the study of field emission characteristics in real time. The calculation of the microscopic characteristics of the local emission sites — the field enhancement factor and emission area — was carried out by several different algorithms. A comparison of the results showed that the algorithms gave close values of the characteristics, which increases the reliability of the estimates made.

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