Recent Progress in Crystal Growth and Conductivity Control of Wide Bandgap Group III Nitride Semiconductors

1998 ◽  
Vol 510 ◽  
Author(s):  
I. Akasaki
Keyword(s):  
Crystal Growth ◽  
High Performance ◽  
Recent Progress ◽  
Materials Science ◽  
Green Light ◽  
Group Iii Nitrides ◽  
Wide Bandgap ◽  
Device Fabrication ◽  
Quantum Well Structures ◽  
Group Iii

AbstractRecent progress in crystal growth of wide bandgap group III nitrides on highly-mismatched substrates has enabled us to produce high-quality GaN, A1GaN, GaInN and quantum well structures. High-performance blue and green light-emitting diodes and room temperature operation of nitride-based laser diodes have also been realized. Today, steady progress is being made in the areas of crystal growth and device performance. However, much further advances are required in many areas of materials science and device fabrication of the nitrides

Growth Kinetics and Thermal Stress in AlN Bulk Crystal Growth

2002 ◽  
Author(s):  
Bei Wu ◽  
Ronghui Ma ◽  
Hui Zhang ◽  
Michael Dudley ◽  
Raoul Schlesser ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Crystal Growth ◽  
Temperature Distribution ◽  
Stress Level ◽  
Grown Crystal ◽  
Power Level ◽  
Chemical Species ◽  
Group Iii Nitrides ◽  
Minor Effect ◽  
Group Iii

Group III nitrides, such as GaN, AlN and InGaN, have attracted a lot of attention due to the development of blue-green and ultraviolet light emitting diodes (LEDs) and lasers. In this paper, an integrated model has developed based on the conservation of momentum, mass, chemical species and energy together with necessary boundary conditions that account for heterogeneous chemical reactions both at the source and seed surfaces. The simulation results have been compared with temperature measurements for different power levels and flow rates in a reactor specially designed for nitride crystal growth at NCSU. It is evident that the heat power level affects the entire temperature distribution greatly while the flow rate has minor effect on the temperature distribution. The results also show that the overall thermal stress level is higher than the critical resolved shear stress, which means thermal elastic stress can be a major source of dislocation density in the as-grown crystal. The stress level is strongly dependent on the temperature gradient in the as-grown crystal. Results are correlated well with defects showing in an X-ray topograph for the AlN wafer.

Channeling defects in group-III nitrides during dry etching processes

2000 ◽  
Vol 622 ◽  
Author(s):  
O. Breitschädel ◽  
J.T. Hsieh ◽  
B. Kuhn ◽  
F. Scholz ◽  
H. Schweizer
Keyword(s):  
Quantum Well ◽  
Incidence Angle ◽  
Ion Beam ◽  
Energy Shift ◽  
Group Iii Nitrides ◽  
Quantum Well Structures ◽  
Group Iii ◽  
Ion Channeling ◽  
Before And After ◽  
Gan Heterostructure

ABSTRACTThe effects of Ar+ ion beam etching (IBE) of AlGaN/GaN heterostructures and GaN/InGaN/GaN quantum well structures were investigated dependent on different ion incidence angles. The AlGaN/GaN heterostructure was measured before and after etching with respect to mobility and sheet resistance. The InGaN quantum well structure was measured with PL to determine the PL intensity and the energy shift, respectively. This experiments show that ion channeling is a significant defect generation phenomena in group- III nitrides at vertical ion incidence angle and can be minimized by tilting the sample against the ion beam.

Renaissance and Progress in Nitride Semiconductors - My Personal History of Nitride Research -

2000 ◽  
Vol 639 ◽  
Author(s):  
Isamu Akasaki
Keyword(s):  
High Speed ◽  
High Performance ◽  
Green Light ◽  
Blue Laser ◽  
Personal History ◽  
Nitride Semiconductors ◽  
Quarter Century ◽  
Group Iii ◽  
History Of ◽  
Group Iii Nitride

ABSTRACTWide bandgap group-III nitride semiconductors are currently experiencing the most exciting development. High brightness blue and green light emitting diodes (LEDs) are commercialized, and UV and blue laser diodes (LDs), high-speed transistors (TRs) and UV photodetectors (PDs) with low dark current, which will be able to operate in harsh environments, have been demonstrated. In this paper, renaissance and progress in crystal growth and conductivity control of nitride semiconductors in the last quarter century are reviewed as the groundwork for all of those high-performance devices. My personal history of nitride research will be also introduced.

Recent Advances in THM CZT for Nuclear Radiation Detection

2009 ◽  
Vol 1164 ◽  
Author(s):  
Jason Mackenzie ◽  
Henry Chen ◽  
Salah A Awadalla ◽  
Pramodha Marthandam ◽  
Bob Redden ◽  
...  
Keyword(s):  
Crystal Growth ◽  
High Performance ◽  
Radiation Detection ◽  
Device Fabrication ◽  
Nuclear Radiation ◽  
Imaging Application ◽  
Growth Method ◽  
Traveling Heater Method ◽  
Diameter Ingot ◽  
Czt Detectors

AbstractThe introduction of large single crystal and high performance CdZnTe (CZT) grown by the traveling heater method (THM) in 2006 has defied conventional myths about the capability of this crystal growth method with respect to the production of spectroscopic grade CZT and its commercialization prospect in medical imaging application. Since then, a lot of progresses have been made, both in the crystal growth and the devices sides. This paper focuses on the development of THM CZT in recent years. Crystalline defects which challenge the thickness scalability of large volume CZT detectors along with efforts and achievements in overcoming these challenges are discussed. Advances in THM CZT crystal growth include 100mm diameter ingot and state-of-the-art device fabrication will also be presented.

Dry and Wet Etching for Group III – Nitrides

1998 ◽  
Vol 537 ◽  
Author(s):  
I. Adesida ◽  
C. Youtsey ◽  
A. T. Ping ◽  
F. Khan ◽  
L. T. Romano ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
Group Iii Nitrides ◽  
Device Fabrication ◽  
Wet Etching ◽  
Microwave Transistors ◽  
Group Iii ◽  
Inductively Coupled ◽  
Dislocation Densities ◽  
High Bond ◽  
Etch Rates

AbstractThe group-III nitrides have become versatile semiconductors for short wavelength emitters, high temperature microwave transistors, photodetectors, and field emission tips. The processing of these materials is significant due to the unusually high bond energies that they possess. The dry and wet etching methods developed for these materials over the last few years are reviewed. High etch rates and highly anisotropic profiles obtained by inductively-coupled-plasma reactive ion etching are presented. Photoenhanced wet etching provides an alternative path to obtaining high etch rates without ion-induced damage. This method is shown to be suitable for device fabrication as well as for the estimation of dislocation densities in n-GaN. This has the potential of developing into a method for rapid evaluation of materials.

Recent progress in wide bandgap conjugated polymer donors for high-performance nonfullerene organic photovoltaics

2020 ◽  
Vol 56 (35) ◽  
pp. 4750-4760 ◽  
Author(s):  
Cunbin An ◽  
Zhong Zheng ◽  
Jianhui Hou
Keyword(s):  
Organic Photovoltaics ◽  
Conjugated Polymer ◽  
High Performance ◽  
Recent Progress ◽  
Wide Bandgap ◽  
Feature Article ◽  
Wide Bandgap Polymer

This feature article summarizes our recent achievements in the development of wide bandgap polymer donors as high-performance organic photovoltaics.

EELS Characterization of Electronic Structure in Group III - Nitrides Compared With Synchrotron Ellipsometry Results

1999 ◽  
Vol 5 (S2) ◽  
pp. 692-693
Author(s):  
G. Brockt ◽  
H. Lakner
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Group Iii Nitrides ◽  
Wide Bandgap ◽  
Loss Peak ◽  
Low Loss ◽  
Group Iii ◽  
Specimen Material ◽  
Wide Bandgap Materials

EELS in the low loss region of the spectra (< 50eV) provides information on excitations of outer shell electrons and thus the electronic structure of a specimen material which determines its optical properties. In this work dedicated EELS methods for the experimental acquisition and analysis of spectra are described which give improved information about the electronic structure near the bandgap region at a spatial resolution in the range of nanometers. For this purpose we made use of a cold field emission STEM equipped with a dedicated EELS system. This device provides a subnanometer electron probe and offers an energy resolution of 0.35 eV. Application of suitable deconvolution routines for removal of the zero loss peak extracts information on the closest bandgap region while Kramers-Kronig transformation deduces the dielectric properties from the measured energy loss function. These methods have been applied to characterize the optical properties of wide-bandgap materials for the case of group Ill-nitride compounds which are currently the most promising material for applications on optoelectronic devices working in the blue and ultraviolet spectral range.

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