bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spectroscopic Identification of the Acceptor-Hydrogen Complex in Mg-Doped GaN Grown by MOCVD
Authors: Götz W. , McCluskey M. D. , Johnson N. M. , Bour D. P. , Haller E. E. 
Published: April 2011

ABSTRACTMg-doped GaN films grown by metalorganic chemical vapor deposition were characterized by variable-temperature Hall-effect measurements and Fourier-transform infrared absorption spectroscopy. As-grown, thermally activated, and deuterated Mg-doped GaN samples were investigated. The existence of Mg-H complexes in GaN is demonstrated with the observation of a local vibrational mode (LVM) at 3125 cm-1 (8 K). At 300 K this absorption line shifts to 3122 cm-1. The intensity of the LVM line is strongest in absorption spectra of as-grown GaN. Mg which is semi-insulating. Upon thermal activation, the intensity of the LVM line significantly decreases and an acceptor concentration of 2×1019cm-3 is derived from the Hall-effect data. After deuteration at 600°C the resistivity of the Mg-doped GaN increased by four orders of magnitude. A LVM line at 2321 cm-1 (8 K) appears in the absorption spectra which is consistent with the isotopie shift of the vibrational frequency when D is substituted for H.
Incorporation and Optical Activation of Er in Group III-N Materials Grown by Metalorganic Molecular Beam Epitaxy
Authors: Mackenzie J. D. , Abernathy C. R. , Pearton S. J. , Donovan S. M. , Hömmerich U. , Thaik M. , Wu X. , Ren F. , Wilsons R. G. , Zavada J. M. 
Published: April 2011

ABSTRACTMetalorganic molecular beam epitaxy has been utilized to incorporate Er into AlGaN materials during growth utilizing elemental and metalorganic sources. Room temperature 1.54 μm photoluminescence was observed from AlN:Er and GaN:Er. Photoluminescence from AlN:Er doped during growth using the elemental source was several times more intense than that observed from implanted material. For the first time, strong room temperature 1.54 μm PL was observed in GaN:Er grown on Si. Temperature-dependent photoluminescence experiments indicated the 1.54 μm intensities were reduced to 60% and 40% for AlN:Er and GaN:Er, respectively, between 15 K and 300 K. The low volatility of Er(III) tris (2,2,6,6 - tetramethyl heptanedionate) and temperature limitations imposed by transport considerations limited maximum doping levels to ∼1017 cm-3 indicating that this precursor is unsuitable for UHV.
Site-Selective Photoluminescence Excitation and Photoluminescence Spectroscopy of Er-Implanted Wurtzite GaN
Authors: Kim S. , Rhee S. J. , Turnbull D. A. , Li X. , Coleman J. J. , Bishop S. G. 
Published: April 2011

ABSTRACTSite-selective photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopy have been carried out at 6K on the ∼1540 nm 4I15/2 → 4I15/2 emissions of Er3+ in Er-implanted GaN. The PLE spectra exhibit several broad, below-gap, defect- or impurity-related absorption bands which excite three distinct site-selective Er + PL spectra. The near-band edge spectral position and lineshape of the PLE spectrum of one of the site-selective PL bands suggest that this Er site forms a trap level within the band gap and an exciton bound at this trap is involved in the excitation mechanism. In addition, high resolution PLE spectra obtained with a tunable laser in the 810 nm spectral range reveal a set of sharp PLE peaks due to the 4I15/2 → 4I9/2 internal Er+ ƒ-band absorption superimposed on the broad defect PLE band. The site-selective PL spectrum excited by the sharp line ∼810 nm Er+ intra-ƒ shell PLE bands is characteristic of a fourth distinct Er+ site. The simple structure of the site-selective PL and PLE spectra associated with direct intra-ƒ shell absorption suggests that the optically active Er site responsible for these spectra is of high symmetry in wurtzite GaN and that it could be attributed to a single Er atom on a Ga site.
GaN Crystals Grown from a Liquid Phase at Reduced Pressure
Authors: Ivantsov V. A. , Sukhoveev V. A. , Dmitriev V. A. 
Published: April 2011

ABSTRACTGallium nitride crystals were grown from a Ga-based melt at an ambient gas pressure not exceeding 2 atm. Growth temperature was about 1000°C. The crystals were 2H-GaN and had a (0001) plane orientation. Crystal size varied from 0.05×0.05×0.01 mm3 to 2×2×0.05 mm3. Lateral growth rate of the crystals ranged from 0.05 to 1 mm/hr. Normal growth rate was about 0.01 mm/hr. Depending on growth conditions, the crystals have a platelet or dendrite shape. Crystals were characterized by optical and electron microscopy, Auger electron spectroscopy, x-ray differential diffraction, photoluminescence and optical absorption. Lattice parameters and band gap value of the grown crystals were determined at 300 K.
Excitons Bound to Stacking Faults in Wurtzite GaN
Authors: Rebane Y. T. , Shreter Y. G. , Albrecht M. 
Published: April 2011

ABSTRACTA model of the exciton bound to stacking faults (SF) in GaN is suggested. It is shown that SFs are potential wells (depth ∼ 120 meV) for electrons and potential barriers (∼ 60 meV) for holes. The binding energy of the exciton at stacking faults is estimated as 30 − 60 meV. The 364 nm line in GaN photoluminescence is attributed to excitons at stacking faults.
High-Pressure Raman Scattering of Biaxially Strained GaN on GaAs
Authors: Siegle H. , Goñi A. R. , Thomsen C. , Ulrich C. , Syassen K. , Schöttker K. , As D. J. , Schikora D. 
Published: April 2011

ABSTRACTWe present results of high-pressure Raman-scattering experiments on bulk GaN and GaN grown on GaAs. We determined the Grüneisen parameters of both the cubic TO and LO phonon modes and the hexagonal A1, E1 and E2 modes. Our measurements reveal that the Grüneisen parameters for the GaAs substrate are about 30% smaller than those of bulk GaAs. This is a consequence of the lower compressibility of GaN compared to GaAs, which results in a pressure-induced biaxial strain on the substrate. From the pressure behavior of the GaAs modes and by comparing with our results for bulk GaN we obtained information about the biaxial strain in the GaN epitaxial layer.
Measurement of InxGa1-xN and AlxGa1-xN Compositions by RBS and SIMS
Authors: Gao Y. , Kirchhoff J. , Mitha S. , Erickson J. W. , Huang C. , Clark-Phelps R. 
Published: April 2011

ABSTRACTSecondary ion mass spectrometry (SIMS) and Rutherford Backscattering Spectrometry (RBS) techniques were used to determine InxGa1-xN and AlxGa1-xN compositions. While RBS is generally considered a quantitative technique for compositional analysis, SIMS has not been. We have applied a new analytical technique, which reduces the matrix effect in SIMS analysis, to accurately determine stoichiometry. The composition of InxGa1-xN (AlxGa1-xN) in the multiple layers and quantum well of the LED can be measured by SIMS, but is inaccessible to RBS.
Luminescence Related to Stacking Faults in Heterepitaxially Grown Wurtzite GaN
Authors: Albrecht M. , Christiansen S. , Salviati G. , Zanotti-Fregonara C. , Rebane Y. T. , Shreter Y. G. , Mayer M. , Pelzmann A. , Kamp M. , Ebeling K. J. , Bremser M. D. , Davis R. F. , Strunk H. P. 
Published: April 2011

ABSTRACTWe correlate structure analyzed by transmission electron microscopy with photo- and cathodoluminescence studies of GaN/Al2O3(0001) and GaN/SiC(0001) and show that an additional UV line at 364nm/3.4eV can be connected to the occurrence of stacking faults. We explain the occurrence of this line by a model that is based on the concept of excitons bound to stacking faults that form a quantum well of cubic material in the wurtzite lattice of the layer material. The model is in reasonable agreement with the experimental observations.
Impurity Contamination of GaN Epitaxial Films From the Sapphire, SiC and ZnO Substrates
Authors: Popovici Galina , Kim Wook , Botchkarev Andrei , Tang Haipeng , Solomon James , Morkoç Hadis 
Published: April 2011

ABSTRACTLikely contamination of GaN films by impurities emanating from Al2O3, SiC and ZnO substrates during growth has been studied by secondary ion mass spectrometry analysis. The highly defective interfacial region allows impurities to incorporate more readily as comparedjo the equilibrium solubility in a perfect crystal at a given temperature as evidenced by increased impurity levels in that region as detected by SIMS. The SIMS measurements in GaN layers grown on SiC and sapphire showed large amounts of Si and O, respectively, within a region wider than the highly disordered interfacial region pointing to the possibility of impurity diffusion at growth temperatures. The qualitative trend observed is fairly clear and significant. These observations underscores the necessity for developing GaN and/or AlN substrates.
Development of GaN and InGaN Gratings by Dry Etching
Authors: Lee J. W. , Hong J. , Mackenzie J. D. , Abernathy C. R. , Pearton S. J. , Ren F. , Sciortino P. F. 
Published: April 2011

ABSTRACTSub-micron periodic gratings with pitch ∼3,000Å were formed in GaN and InGaN using holographic lithography and room temperature ECR BCl3/N2 dry etching at moderate microwave (500W) and rf (100W) powers. The process produces uniform gratings without the need for elevated sample temperatures during the etch step.
ICP Dry Etching of III-V Nitrides
Authors: Vartuli C. B. , Lee J. W. , MacKenzie J. D. , Donovan S. M. , Abernathy C. R. , Pearton S. J. , Shul R. J. , Constantine C. , Barrati C. , Katz A. , Poyakov A. Y. , Shin M. , Skowronski M. 
Published: April 2011

ABSTRACTInductively coupled plasma etching of GaN, AlN, InN, InGaN and InAlN was investigated in CH4/H2/Ar plasmas as a function of dc bias, and ICP power. The etch rates were generally quite low, as is common for III-nitrides in CH4 based chemistries. The etch rates increased with increasing dc bias. At low rf power (150W), the etch rates increased with increasing ICP power, while at 350W rf power, a peak was found between 500 and 750 W ICP power. The etched surfaces were found to be smooth, while selectivities of etch were ≤ 6 for InN over GaN, AlN, InGaN and InAlN under all conditions.
Recovery of Structural Defects in GaN After Heavy Ion Implantation
Authors: Running C. , Dalmer M. , Deicher M. , Restle M. , Bremser M. D. , Davis R. F. , Hofsäss H. 
Published: April 2011

ABSTRACTSingle crystalline GaN-layers were implanted with radioactive 111In ions. The lattice location of the ions and the recovery of the implantation induced damage was studied using the emission channeling technique and perturbed-γγ-angular-correlation spectroscopy as a function of the annealing temperature. We find the majority of indium atoms on substitutional sites even directly after room temperature implantation, but within a heavily disturbed surrounding. During isochronal annealing treatments in vacuum, a gradual recovery of the implantation damage takes place between 873 K and 1173 K. After 1173 K annealing about 50 % of the In atoms occupy substitutional lattice sites with defect free surroundings.
Temperature Behavior of Pt/Au Ohmic Contacts to p-GaN
Authors: King D. J. , Zhang L. , Ramer J. C. , Hersee S. D. , Lester L. F. 
Published: April 2011

ABSTRACTOhmic contacts to Mg-doped p-GaN grown by MOCVD [1] are studied using a circular transmission line model (TLM) to avoid the need for isolation. For samples which use a p-dopant activation anneal before metallization, no appreciable difference in the specific contact resistance, rc, as a function of different capping options is observed. However, a lower rc is obtained when no pre-metallization anneal is employed, and the post-metallization anneal simultaneously activates the p-dopant and anneals the contact. This trend is shown for Pt/Au, Pt, Pd/Pt/Au, and Ni/Au contacts to p-GaN. The rc 's for these metal contacts are in the range of 1.4–7.6 × 10-3 ohm-cm2 at room temperature at a bias of 10mA. No particular metallization formula clearly yields a consistently superior contact. Instead, the temperature of the contact has the strongest influence.Detailed studies of the electrical properties of the Pt/Au contacts reveal that the I-V linearity improves significantly with increasing temperature. At room temperature, a slightly rectified I-V characteristic curve is obtained, while at 200°C and above, the I-V curve is linear. For all the p-GaN samples, it is also found that the sheet resistance decreases by an order of magnitude with increasing temperature from 25°C to 350°C. The specific contact resistance is also found to decrease by nearly an order of magnitude for a temperature increase of the same range. A minimum rc of 4.2 × 10-4 ohm-cm2 was obtained at a temperature of 350°C for a Pt/Au contact. This result is the lowest reported rc for ohmic contacts to p-GaN.
Optimization of III-N Based Devices Grown by RF Atomic Nitrogen Plasma Using In-Situ Cathodoluminescence
Authors: Van Hove J. M. , Chow P. P. , Klaassen J. J. , Hickman R. , Wowchak A. M. , Croswell D. R. , Polley C. 
Published: April 2011

ABSTRACTIn-situ cathodoluminescence (CL) is presented as a technique to optimize GaN, and AlGaN films deposited by MBE using an RF plasma as a source of reactive nitrogen. Excitation of the MBE grown nitride films is conveniently achieved in the preparation chamber using an Auger electron gun. The photoemission is monitored through a side port and dispersed with a 1/8 m monochromator with a typical resolution of 3 nm. The in-situ CL spectra of AlGaN and GaN films provides quick determination of both material composition, doping, and quality from the position and width of the band edge emission. The use of CL for the assessment of material composition in the growth of nitride materials is extremely beneficial since the complementary technique of RHEED oscillations is not routinely observed for these systems. The determination of material quality using CL has been used to optimize growth conditions for GaN PIN junction photovoltaic detectors on (0001) sapphire. Detectors having peak responsivity of 0.175 AAV at the GaN band edge of 365 nm and a UV to visible rejection ratio of greater than 105 have been fabricated. The high rejection ratio is accredited to the reduction of the yellow defect levels in the MBE grown material. Material optimization using in-situ CL for growth of AlGaN MODFETs having drain currents of 425 ma/mm and gm of 66 mS/mm is discussed.
Reliable, Reproducible and Efficient MOCVD of III-Nitrides in Production Scale Reactors
Authors: Wachtendorf B. , Beccard R. , Schmitz D. , Jürgensen H. , Schön O. , Heuken M. , Woelk E. 
Published: April 2011

ABSTRACTIn this paper we present a class of MOCVD reactors with loading capacities up to seven 2″ wafers, designed for the mass production of LED structures.Our processes yield device quality GaN with excellent PL uniformities better than 1 nm across a 2″ wafer and thickness uniformities typically better than 2%.We also present full 2″ wafer mapping data, High Resolution Photoluminescence Wafer Scanning and sheet resistivity mapping, revealing the excellent composition uniformity of the nitride compounds InGaN and AlGaN. As well we will show sheet resistivity uniformity for Si-doped GaN and Mg-doped GaN.
Pyrolytic Preparation of Gallium Nitride From [Ga(NEt2)3]2 and its Ammonolysis Compound
Authors: Koyama Seiichi , Sugahara Yoshiyuki , Kuroda Kazuyuki 
Published: April 2011

AbstractGallium nitride (GaN) was prepared by the pyrolytic conversion of both [Ga(NEt2)3]2 and its ammonolysis product at 600 °C for 4 h under Ar. The pyrolyzed residues were analyzed by X-ray powder diffraction and scanning electron microscopy, and the pyrolysis processes of the precursors under He were investigated by thermogravimetry-mass spectrometry. The XRD pattern of the pyrolyzed residue of [Ga(NEt2)3]2 showed well-resolved peaks due to a mixture of cubic and hexagonal close-packed layers of GaN. The broad XRD pattern of the pyrolyzed residue of the ammonolysis product was also attributed to the mixture of cubic and hexagonal close-packed layers of GaN. For the pyrolysis of [Ga(NEt2)3]2, the evolution of hydrocarbons was extensively observed at relatively high temperature, but a large amount of carbon (11 mass%) was still detected in the pyrolyzed residue. On the other hand, the amount of carbon was only 1.1 mass% in the pyrolyzed residue of the ammonolysis product. The pyrolysis results of the ammonolysis product under Ar were very similar to those of [Ga(NEt2)3]2 under NH3.
Effect of C and Ge Concentration On The Thermal Stability of RTCVD Grown Si1-x-yGexCy Alloys
Authors: Warren Patricia , Retzmanick Stephane , Gotza Martin , Begems Marc 
Published: April 2011

ABSTRACTSi / Si1-x-yGexCy / Si heterostructures containing up to 17 at.% Ge and 1.9 at.% C were grown on (001) silicon by low pressure Rapid Thermal Chemical Vapor Deposition, using a mixture of silane, germane and methylsilane, diluted in hydrogen. The samples were then annealed in a Rapid Thermal Processing furnace, under an atmospheric pressure of nitrogen, at temperatures ranging from 900 to 1130 °C.The samples were characterized using infrared spectroscopy and x-ray diffraction. SIMS profiling and TEM observation were performed on some of the samples.Substitutional C gradually disappeared, either precipitating out to form cubic silicon carbide (β-SiC), or simply vanishing into interstitial positions. In any case, the in-plane lattice constant remained constant after annealing, indicating that there was no mechanical strain relaxation by formation of misfit dislocations. The perpendicular lattice constant increased due to the decrease in substitutional C concentration, as well as it decreased due to the germanium out-diffusion. This variation of the strain during annealing was modeled, and allowed the determination of the kinetics of the substitutional carbon disappearance. The same behavior was observed for all samples. Indeed, the Cs disappearance rate was always increased for samples with higher initial Ge and C concentrations. The kinetics of this precipitation was found in very good agreement with previous published results.
The Growth of β-SiC on Si and Poly-Si on β-SiC by Rapid Thermal Chemical Vapor Deposition
Authors: Liu C. W. , Sturm J. C. 
Published: April 2011

ABSTRACTThe growth properties of β-SiC on (100) Si grown by rapid thermal chemical vapor deposition, using a single precursor (methylsilane) without an initial surface carbonization step, were investigated. An optimun growth temperature at 800°C was found to grow single crystalline SiC. The single crystalline SiC films were used to be the buffer layers for the growth of subsequent poly Si films. For the poly Si grown at low temperature (625°C), the (110) Si diffraction was found to be the dominant peak in the X-ray diffraction spectra at the initial growth stage, while the poly Si grown on oxide was dominated by (111) texture. A small average misfit (4 %) between (110) Si planes and (100) SiC planes was proposed to explain this effect. To apply the Si/SiC/Si multilayers, SiC/Si heterojunction bipolar transistors (HBT's) were fabricated and compared to Si bipolar junction transistors.
Rapid Thermal Processing: When Will it Replace Batch Processing?
Authors: Pas M. F. , Pas S. D. 
Published: April 2011

ABSTRACTRapid Thermal Processing (RTP) is currently well established at the < 0.5 μm nodes for implant anneal and suicide formation/anneal in logic applications. Rapid Thermal Chemical Vapor Deposition (RTCVD) is being evaluated to deposit thin nitride for the DRAM storage node dielectric. A combination RTP/RTCVD has been evaluated in the form of a cluster tool to evaluate 60 Å gate oxides. These applications of RTP are considered to be process enabling because of either improved temperature ramp control or ambient control which are not available in batch processing. However, even with these specialized applications, rapid thermal processing comprises less than 20% of the front end thermal processes in a typical 0.35 μm fab. Process and equipment issues with rapid thermal processing remain which must be overcome if it is to replace batch processing at the 0.25 μm node. Process issues which are especially critical for RTCVD processing require improved temperature measurement, high growth/deposition rate, and an efficient method of cleaning the process chamber. Equipment issues are reliability and throughput which directly affect the tool cost of ownership. In this paper, each of these issues will be addressed and compared to batch processing using a generic logic process flow.
The Performance of The Fast Ramp Vertical Furnace
Authors: Torres Kenneth , Lam Denny , Weaver Robert , Solomon Gary 
Published: April 2011

AbstractThis paper summarizes a Joint Development Project between SEMITOOL, member company and SEMATECH to demonstrate and develop the fast ramp vertical furnace. The goal of this project was to deliver a production vertical furnace capable of heating and cooling a batch of 50 wafers at average ramp rates of 75 and 50 °C/min, respectively. The furnace did meet these goals. This paper will outline the distinctive and enabling design features of the furnace, such as the use of model predictive control techniques to stabilize the wafer temperatures within 2 to 5 minutes of reaching the nominal target temperature. The test results of a ten run passive data collection for a 145 ohm/sq boron S/D anneal and a 65 angstrom gate oxidation process will be discussed. The boron S/D anneal PDC results exceeded the 3 sigma standard deviation for all points goal of 5.0%. The gate oxidation PDC gave a mean of 65 angstroms and met its 3 sigma standard deviation for all points goal of 4.5%. Using an unyielded model (defect density=0) the cost of ownership is estimated to be $3.02/wafer for a 50 wafer load and as low as $1.68 for a 200 wafers load for a gate oxide process. The fast ramp vertical furnace is designed to meet 0.25 and 0.18 micron technology needs, improve cycle time, and give the customer the flexibility of using different wafer batch sizes within a 25” flat temperature zone (where the ramp rates are adjusted according to the wafer pitch).
Formation of Titanium Silicide on Ion-Implanted Silicon
Authors: Gilboa Y.E , Eizenberg M. 
Published: April 2011

AbstractThe formation of TiSi2 was compared over samples implanted with arsenic and BF2 at different doses and annealed at different temperatures and lengths of time in a rapid thermal process. Measurements were done to determine the composition and thickness of the suicide formed. The composition was determined from Auger electron spectroscopy, Rutherford backscattering spectroscopy, and transmission electron microscopy. The phase formation of the suicide was characterized by X-ray diffraction. Dopant redistribution was studied using secondary ion mass spectroscopy. Comparing the results of the different implant doses we found that the amount of suicide formed over heavily doped Si at formation temperatures of 600°C to 650°C was reduced compared to undoped Si. At formation temperatures above 750°C the implanted dose and species did not significantly affect the amount of suicide formation. Above 750°C the TiSi2 structure was found to be the C54 phase. Arsenic was found to diffuse into the Ti suicide layer in a diffusion controlled process. Boron was found to accumulate at the Ti suicide interfaces both with the substrate and with the surface TixOyNz layer.
Problems with The Concept of Thermal Budget: Experimental Demonstrations
Authors: Ditchfield R. , Seebauer E. G. 
Published: April 2011

ABSTRACTUp to now, kinetic effects in rapid thermal processing (RTP) have been assessed using the concept of thermal budget, with the idea that thermal budget minimization should minimize dopant diffusion and interface degradation. This work highlights shortcomings with that principle. Experiments comparing directly the rate of Si chemical vapor deposition with that of dopant diffusion show how thermal budget minimization can actually worsen diffusion problems rather than mitigate them. We present a straightforward framework for improving the results through comparison of activation energies of the desired and undesired phenomena. This framework explains the experimental results and provides strong kinetic arguments for continued development of rapid isothermal processing and small batch fast ramp methods.