Exafs Studies of Group III-Nitrides

1998 ◽  
Vol 512 ◽  
Author(s):  
N J Jeffs ◽  
A V Blant ◽  
T S Cheng ◽  
C T Foxon ◽  
C Bailey ◽  
...  
Keyword(s):  
Phase Separation ◽  
High Frequency ◽  
Group Iii Nitrides ◽  
Total Electron Yield ◽  
Interatomic Distances ◽  
Total Electron ◽  
Group Iii ◽  
Bond Lengths ◽  
Group Iii Nitride ◽  
Comprehensive Study

ABSTRACTThe group III nitrides have important applications for blue/green LEDs, blue/UV laser diodes and for high-power high frequency FETs. In all such devices the alloys play an important role either in the active part of the structure or in the cladding regions. The properties of the group III-nitride alloys are not at present well understood and in particular there are indications that phase separation can occur. We have undertaken a comprehensive study of (InGa)N alloys using EXAFS in order to study such problems.We have demonstrated recently that REFLEXAFS technique can be used to give interatomic distances for (InGa)N alloys using the In edge to measure the bond lengths as a function of In content over the complete range from InN to GaN. We have now extended this study by using the Total Electron Yield (TEY) EXAFS technique to study the bond lengths by using both the Ga and In edges for (InGa)N alloys. The TEY data for the (InGa)N alloy samples gives more reliable data for the In-In and In-Ga separations than the earlier REFLEXAFS studies. Data obtained for the In-Ga separation from the Ga and In edges agree well within experimental error.The data obtained from this study suggest that the (InGa)N samples grown at low temperature do not exhibit evidence for phase separation.

Pressure Dependence of Optical Transitions in In-rich Group III-Nitride Alloys

2003 ◽  
Vol 798 ◽  
Author(s):  
S. X. Li ◽  
J. Wu ◽  
W. Walukiewicz ◽  
W. Shan ◽  
E. E. Haller ◽  
...  
Keyword(s):  
Pressure Dependence ◽  
Pressure Coefficient ◽  
Accurate Method ◽  
Group Iii Nitrides ◽  
Localized States ◽  
Optical Transitions ◽  
Group Iii ◽  
Pressure Coefficients ◽  
Nitride Alloys ◽  
Group Iii Nitride

ABSTRACTThe hydrostatic pressure dependence of the optical transitions in InN, In-rich In1-xGaxN (0 < x < 0.5) and In1-xAlxN (x = 0.25) alloys is studied using diamond anvil cells. The absorption edges and the photoluminescence peaks shift to higher energy with pressure. The pressure coefficient of InN is determined to be 3.0±0.1 meV/kbar. Together with previous experimental results, our data suggest that the pressure coefficients of group-III nitride alloys have only a weak dependence on the alloy composition. Photoluminescence gives much smaller pressure coefficients, which is attributed to emission involving highly localized states. This indicates that photoluminescence might not be an accurate method to study the pressure dependence of the fundamental bandgaps of group III-nitrides.

MOCVD Growth of Group III Nitrides for High-power, High-frequency Applications

2005 ◽  
pp. 69-94
Author(s):  
M.A. di Forte-Poisson ◽  
M. Magis ◽  
M. Tordjmann ◽  
J. di Persio
Keyword(s):  
High Power ◽  
High Frequency ◽  
Group Iii Nitrides ◽  
Group Iii ◽  
Mocvd Growth

MOCVD growth of group III nitrides for high power, high frequency applications

2005 ◽  
Vol 2 (3) ◽  
pp. 947-955 ◽  
Author(s):  
M.-A. di Forte Poisson ◽  
M. Magis ◽  
M. Tordjman ◽  
N. Sarazin ◽  
J. di Persio
Keyword(s):  
High Power ◽  
High Frequency ◽  
Group Iii Nitrides ◽  
Group Iii ◽  
Mocvd Growth

scholarly journals Preparation of the group III nitride thin films AlN, GaN, InN by direct and reactive pulsed laser ablation

2001 ◽  
Vol 3 (3) ◽  
pp. 111-121 ◽  
Author(s):  
Aldo Mele ◽  
Anna Giardini ◽  
Tonia M. Di Palma ◽  
Chiara Flamini ◽  
Hideo Okabe ◽  
...  
Keyword(s):  
Thin Films ◽  
Laser Ablation ◽  
Group Iii Nitrides ◽  
X Ray Diffraction ◽  
Subsequent Reaction ◽  
X Ray ◽  
Group Iii ◽  
Emission Spectroscopic Analysis ◽  
Group Iii Nitride

The methods of preparation of the group III nitrides AlN, GaN, and InN by laser ablation (i.e. laser sputtering), is here reviewed including studies on their properties. The technique, concerns direct ablation of nitride solid targets by laser to produce a plume which is collected on a substrate. Alternatively nitride deposition is obtained as a result of laser ablation of the metal and subsequent reaction in anNH3atmosphere. Optical multichannel emission spectroscopic analysis, and time of flight (TOF) mass spectrometry have been applied forin situidentification of deposition precursors in the plume moving from the target. Epitaxial AlN, GaN, and InN thin films on various substrates have been grown. X-ray diffraction, scanning electron microscopy, have been used to characterise thin films deposited by these methods.

scholarly journals Phase separation and ordering in group-III nitride alloys

2004 ◽  
Vol 34 (2b) ◽  
pp. 593-597 ◽  
Author(s):  
L. K. Teles ◽  
M. Marques ◽  
L. M. R. Scolfaro ◽  
J. R. Leite ◽  
L. G. Ferreira
Keyword(s):  
Phase Separation ◽  
Group Iii ◽  
Nitride Alloys ◽  
Group Iii Nitride

AlGaN/GaN Based Heterostructures for MEMS and NEMS Applications

2010 ◽  
Vol 159 ◽  
pp. 27-38
Author(s):  
Volker Cimalla ◽  
C. C. Röhlig ◽  
V. Lebedev ◽  
Oliver Ambacher ◽  
Katja Tonisch ◽  
...  
Keyword(s):  
Microelectromechanical Systems ◽  
Longitudinal Vibration ◽  
Wide Band ◽  
Group Iii Nitrides ◽  
Vibration Modes ◽  
Wide Band Gap ◽  
Group Iii ◽  
Wide Band Gap Semiconductors ◽  
Dimensional Electron Gas ◽  
Group Iii Nitride

With the increasing requirements for microelectromechanical systems (MEMS) regarding stability, miniaturization and integration, novel materials such as wide band gap semiconductors are receiving more attention. The outstanding properties of group III-nitrides offer many more possibilities for the implementation of new functionalities and a variety of technologies are available to realize group III-nitride based MEMS. In this work we demonstrate the application of these techniques for the fabrication of full-nitride MEMS. It includes a novel actuation and sensing principle based on the piezoelectric effect and employing a two-dimensional electron gas confined in AlGaN/GaN heterostructures as integrated back electrode. Furthermore, the actuation of flexural and longitudinal vibration modes in resonator bridges are demonstrated as well as their sensing properties.

scholarly journals Novel approach to simulation of group-III nitrides growth by MOVPE

1999 ◽  
Vol 4 (1) ◽  
Author(s):  
S. Yu. Karpov ◽  
V. G. Prokofyev ◽  
E. V. Yakovlev ◽  
R. A. Talalaev ◽  
Yu. N. Makarov
Keyword(s):  
Growth Process ◽  
Solid Phase ◽  
Molecular Nitrogen ◽  
Horizontal Tube ◽  
Group Iii Nitrides ◽  
Process Conditions ◽  
Group Iii ◽  
Novel Approach ◽  
Kinetic Effects ◽  
Group Iii Nitride

Recent studies revealed specific features of chemical processes occurring on the surface of growing group-III nitrides – extremely low sticking probability of molecular nitrogen, low sticking coefficient and incomplete decomposition of ammonia frequently used as the nitrogen precursor. These features (kinetic by nature) result in the growth process going on under conditions remarkably deviated from the gas-solid heterogeneous equilibrium. In this paper we propose a novel approach to modeling of group-III nitride growth by MOVPE taking into account these features. In the model the sticking/evaporation coefficients of N2 and NH3 extracted from independent experiments are used allowing adequate description of the kinetic effects. The model is applied to analysis of growth of binary (GaN) and ternary (InGaN) compounds in a horizontal tube reactor. The growth rate and the solid phase composition are predicted theoretically and compared with available experimental data. The modeling results reveal lower ammonia decomposition ratio on the surface of the crystal as compared to thermodynamic expectations. The developed model can be used for optimization of growth process conditions.

scholarly journals Group-III Nitride ETCH Selectivity IN BCl /Cl ICP Plasmas

1999 ◽  
Vol 4 (S1) ◽  
pp. 823-833 ◽  
Author(s):  
R. J. Shul ◽  
L. Zhang ◽  
C. G. Willison ◽  
J. Han ◽  
S. J. Pearton ◽  
...  
Keyword(s):  
Plasma Chemistry ◽  
Optical Emission ◽  
Group Iii Nitrides ◽  
Plasma Etch ◽  
Source Power ◽  
Group Iii ◽  
Inductively Coupled ◽  
Etch Rates ◽  
Group Iii Nitride ◽  
Coupled Plasmas

Patterning the group-III nitrides has been challenging due to their strong bond energies and relatively inert chemical nature as compared to other compound semiconductors. Plasma etch processes have been used almost exclusively to pattern these films. The use of high-density plasma etch systems, including inductively coupled plasmas (ICP), has resulted in relatively high etch rates (often greater than 1.0 µm/min) with anisotropic profiles and smooth etch morphologies. However, the etch mechanism is often dominated by high ion bombardment energies which can minimize etch selectivity. The use of an ICP-generated BCl3 /Cl2 plasma has yielded a highly versatile GaN etch process with rates ranging from 100 to 8000 Å/min making this plasma chemistry a prime candidate for optimization of etch selectivity. In this study, we will report ICP etch rates and selectivities for GaN, AlN, and InN as a function of BCl3/Cl2 flow ratios, cathode rf-power, and ICP-source power. GaN:InN and GaN:AlN etch selectivities were typically less than 7:1 and showed the strongest dependence on flow ratio. This trend may be attributed to faster GaN etch rates observed at higher concentrations of atomic Cl which was monitored using optical emission spectroscopy (OES).

The role of gaseous species in group-III nitride growth

1997 ◽  
Vol 2 ◽  
Author(s):  
S. Yu. Karpov ◽  
Yu. N. Makarov ◽  
M. S. Ramm
Keyword(s):  
Defect Formation ◽  
Lattice Mismatch ◽  
Solid Phase ◽  
Molecular Nitrogen ◽  
Group Iii Nitrides ◽  
Miscibility Gap ◽  
Gaseous Species ◽  
Group Iii ◽  
Ternary Compounds ◽  
Group Iii Nitride

A quasi-thermodynamic model accounting for kinetics of molecular nitrogen evaporation is applied to simulate the growth of binary and ternary group-III nitrides using atomic group-III elements and molecular ammonia as the sources. The values of the molecular nitrogen evaporation coefficients from the surface of GaN and AlN necessary for the simulation are extracted from experiments on free evaporation of the crystals in vacuum, while for InN only estimates are available. The growth process of AlN and InN is studied by analyzing the composition of the desorbed vapor species that are thought to influence the native defect formation in group-III nitrides. Different channels of desorption from the surfaces of group-III nitrides (related either to group-III atoms or to their hydrides) are compared. Specific features of the growth processes under the metal-rich and N-rich conditions are analyzed. The developed approach is extended to study the growth of the ternary compounds GaInN and AlGaN. The growth rate of ternary compounds versus temperature shows a two-drop behavior corresponding to the rapid increase of the respective group-III atom desorption. The effect is accompanied by a corresponding stepwise change in the solid phase composition. Factors retarding the growth of ternary compounds — the miscibility gap related to internal strain accumulated in the solid phase due to the lattice mismatch of binary constituents, and the extra liquid phase formation during growth — are discussed with respect to GaInN.

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