bluuebunny/crossref_metadata_2025_split huggingface dataset:
Monte Carlo Simulation of Transient Currents in a-Si:H
Authors: Chen Wen Chao , hamel Louis-André 
Published: April 2011

AbstractMulti-trapping transient currents through pure exponential band tails are calculated by Monte Carlo simulations of unprecedented accuracy. The time and energy dependent carrier distributions, the current and the charge signals are obtained. The transit time tT and the dispersion parameters α1, and α2, before and after the transit time, are extracted from the simulated currents. Results are presented for the expected temperature dependence of α1 and α2 and of the drift mobility μD for electrons and holes in a-Si:H. At low temperature, α1 = α2 = T/To is found, but above T ≈ 0.6To, α1, bends downwards to saturate at 1 at high temperature while α2 bends upwards, clearly improving the agreement with the experimental data. The temperature dependence of the drift mobility μD is well reproduced for holes with a microscopic mobility of μo = 0.5 cm2V−1s−1. For electrons, the agreement is also excellent but the surprisingly low value of μo = 4 cm2V−1s−1 is found.
Study of Recombination Processes in a-Si:H by the Temperature Dependence of the two Carriers Phototransport Properties
Authors: Lubianiker Y. , Naidis R. , Balberg I. , Fonseca L. , Weisz S. Z. 
Published: April 2011

AbstractWe have studied films of undoped hydrogenated amorphous silicon by measuring their phototransport properties as a function of temperature. The samples were prepared by decomposition of silane using either the rf glow discharge or the hot-wire techniques. Both materials exhibit similar temperature dependences of the phototransport properties. The main difference is that the thermal quenching effects in the hot-wire material occur at a lower temperature. The results are consistent with the “standard” recombination model, to which recombination through the bandtails is added. The differences in the thermal quenching effects are attributed to the higher density of conduction bandtail states in the hot-wire material, and to differences in the position of the Fermi level with respect to the dangling bond states.
Transport Properties of Compensated μc-Si:H
Authors: Wyrsch N. , Goerlitzer M. , Beck N. , Meier J. , Shah A. 
Published: April 2011

AbstractElectron and hole transport in completely microcrystalline silicon (μc-Si) p-i-n cells and in intrinsic or near intrinsic μc-Si layers have been investigated, for the first time, by time of flight (TOF) at temperatures between 100 and 400 K.At room temperature, both electron and hole drift mobilities were found to be between 0.2 and 1 cm2 V-ls-1. No trace of anomalous dispersive transport was observed, neither for electrons nor for holes, down to 100 K. A decrease of the drift mobility was observed when the temperature was raised from room temperature to 400 K as usually observed in crystalline semiconductors. However, these experimental values of the drift mobilities appear more puzzling than helpful for the comprehension of this “new” photovoltaic material.
Optoelectronic Properties of Thin Amorphous and Micro-Crystalline p-Type Films Developed for Amorphous Silicon-Based Solar Cells
Authors: Winz K. , Rech B. , Eickhoff T. H. , Beneking C. , Fortmann C. M. , Hapke P. , Wagner H. 
Published: April 2011

AbstractVIIF-PECVD at 110 MI-z was used to deposit micro-crystalline p-layers on glass substrates for detailed analysis and onto ZnO coated substrates for incorporation into p-i-n solar cell structures. Solar cell and film analysis confirmed that the films incorporated into the solar cells contained significant crystalline silicon volume fractions despite being only 30 nm thick. The p-i-n solar cells employing a micro-crystalline silicon p-layer deposited on ZnO coated substrates had series resistances, fill factors and Voc similar to those of the reference solar cells deposited onto SnO2 coated substrates and having optimized amorphous silicon-carbon p-layers. The short circuit current of the micro-crystalline p-layer case was 10 percent lower than that of the reference cell indicating that further optimization is required.
Surface Roughness of Silicon-Nitride Gate Insulators Deposited in a 40-MHZ Glow Discharge
Authors: Meiling H. , Grotenhuis E. Ten , Weg W. F. Van Der , Hautala J. J. , Westendorp J. F. M. 
Published: April 2011

AbstractThe surface morphology of 40-MHz PECVD SiNx films is investigated. We report on the correlation between the deposition conditions, bulk properties, and surface roughness of these TFT insulators. The roughness is measured with atomic-force microscopy, AFM. A link will be presented between the AFM properties and the effects of hydrogen dilution during deposition: gas composition and rf-power-density (P) dependences will be discussed. An increase of the surface roughness to 3.7 nm is observed upon H2 dilution and P increase, ascribed to enhanced ion bombardment of the surface during growth.
Band-Structure Engineering in Novel Optoelectronic Devices
Authors: Shen H. , Dutta M. 
Published: April 2011

AbstractIn this paper we show that unconventionally strained semiconductor heterostructures with unusual band structure exhibit novel and desirable electronic and optical properties not seen in the conventional strained materials. In addition to improving the performance of existing components, unconventional strain may be used to achieve greater functionality in novel optoelectronic devices. We give as examples three such devices that we have conceived and demonstrated, in the two areas of strain, lattice mismatch induced and thermal expansion coefficient mismatch induced. The higher performance and functionality in these devices demonstrate that strain engineered heterostructures are a very promising area for device research and development.
Dry Etching of SiC for Advanced Device Applications
Authors: Flemish J. R. , Xie K. , Mclane G. F. 
Published: April 2011

AbstractIn this paper we review and compare most of the published results on dry etching of silicon carbide using various techniques. The vast majority of reports have used RIE methods due to the wide availability of such reactors. Recently, alternative methods of magnetron enhanced RIE (MIE) and electron cyclotron resonance (ECR) plasmas have been demonstrated. MIE has resulted in extremely high etch rates and ECR etching has resulted in smooth, residue-free surfaces with an ability to control the etched profiles.
Studies of Degradation in Nichia AlGaN/InGaN/GaN Blue Light Emitting Diodes Under Close to Normal Operating Conditions
Authors: Osiński M. , Barton D. L. , Helms C. J. , Perlin P. , Berg N. H. , Sartori P. , Phillips B. S. 
Published: April 2011

AbstractThe reliability of devices fabricated in GaN and related alloys, especially under high current densities as would be found in lasers, has yet to be fully characterized. Our previous work [1] investigated the degradation of GaN-based blue light emitting diodes (LEDs) under high pulsed current stress. This work indicated a possible correlation between the high crystal defect density and failures caused by metal migration along these defect tubes. To assess the impact of this data on devices under more normal conditions, several LEDs from both older and more recent production lots were placed in a controlled temperature and current environment for several thousand hours. The test started with a constant 20 mA current for the first 1000 hours and continued for another 1650 hours at various currents up to 70 mA, all at a temperature of 23 °C. During this test, one of the older generation LED's output degraded by more than 50%. Subsequent failure analysis showed that this was caused by a crack which isolated part of the active region from the p-contact. The remaining LEDs were returned to life testing where the temperature was subsequently increased by 5 °C after each 500 hours of testing. The output from one of the newer LEDs dreiven at 70 mA degraded to 55% of its original value after 3600 hours and a second newer LED degraded by a similar amount after 4400 hours. The first failure, LED #16, did not exhibit a significant change in its I-V characteristics indicating that a change in the package transparency was a likely cause for the observed degradation. The second failure, LED #17, did show a noticeable change in its I-V characteristics. This device was subsequently returned to life testing where the degradation process will be monitored for further changes.
Ion Implantation For High Performance Ill-V Jfets And Hfets
Authors: Zolper J. C. , Baca A. G. , Sherwin M. E. , Klem J. F. 
Published: April 2011

AbstractIon implantation has been an enabling technology for the realization of many high performance electronic devices in III-V semiconductor materials. We report on advances in ion implantation processing technology for application to GaAs JFETs, AlGaAs/GaAs HFETs, and InGaP or InA1P-barrier HFETs. In particular, the GaAs JFET has required the development of shallow p-type implants using Zn or Cd with junction depths down to 35 nm after the activation anneal. Implant activation and ionization issues for AlGaAs will be reported along with those for InGaP and InAlP. A comprehensive treatment of Si-implant doping of AlGaAs is given based on the donor ionization energies and conduction band density-of-states dependence on Al-composition. Si and Si+P implants in InGaP are shown to achieve higher electron concentrations than for similar implants in AlGaAs due to the absence of the deep donor (DX) level. An optimized P co-implantation scheme in InGaP is shown to increase the implanted donor saturation level by 65%.
Cl2-Based ECR Etching of InGaP, AlInP and AIGaP
Authors: Hong J. , Lee J. W. , Pearton S. J. , Santana C. , Abernathy C. R. , Hobson W. S. , Ren F. 
Published: April 2011

AbstractHigh microwave power (1000W) Electron Cyclotron Resonance (ECR) Cl2/Ar plasma produce etch rates for In0.5Ga0.5P, Al0.5In0.5P and Al0.5Ga0.5P of ˜1um/min. at low pressure (1.5mTorr), moderate rf power levels (150W) and room temperature. Addition of Cl2 into Ar makes much smoother etched surface morphology as well as increasing the etch rate. All parameters, including microwave power, chamber pressure and rf power increase the etch rate of these alloys. Especially, there is at least a minimum rf power in order to get much higher etch rate with increasing microwave power. AlGaP in Cl2/Ar discharges has lower etch rates than InGaP or AlInP, which is similar to the results based on CH4/H2/Ar plasma chemistries. The Cl2/Ar chemistry enables smooth, high-rate etching without the need for polymer addition and thus simplifies the processing.
Plasma Chemistries for Dry Etching GaN, AIN, InGaN and InAIN
Authors: Pearton S. J. , Vartuli C. B. , Lee J. W. , Donovan S. M. , MacKenzie J. D. , Abernathy C. R. , Shul R. J. , McLane G. F. , Ren F. 
Published: April 2011

AbstractEtch rates up to 7,000Å/min. for GaN are obtained in Cl2/H2/Ar or BCl3/Ar ECR discharges at 1–3mTorr and moderate dc biases. Typical rates with HI/H2 are about a factor of three lower under the same conditions, while CH4/H2 produces maximum rates of only ˜2000Å/min. The role of additives such as SF6, N2, H2 or Ar to the basic chlorine, bromine, iodine or methane-hydrogen plasma chemistries are discussed. Their effect can be either chemical ( in forming volatile products with N) or physical ( in breaking bonds or enhancing desorption of the etch products). The nitrides differ from conventional III-V's in that bondbreaking to allow formation of the etch products is a critical factor. Threshold ion energies for the onset of etching of GaN, InGaN and InAlN are ≥75eV.
Movpe of Inp and Gaas Based Optoelectronic Materials in a Multiwafer Production Reactor Using Tba and Tbp Exclusively
Authors: Schmitz D. , Lengeling G. , Beccard R. , Jürgensen H. 
Published: April 2011

AbstractIn this paper a study of the growth of GaAs and InP based materials using the alternative precursors TBAs and TBP is presented. For this purpose mass production multiple wafer reactors were employed. Both long-wavelength materials such as GaInAsP on IWP and short wavelegth like GaInP and AIGaInP on GaAs are investigated. The results demonstrate that ther is no loss of material quality when using these novel precursors. In all cases growth temperatures and V/III ratios could be significantly lowered.
The Growth and Doping of Al(As)Sb by Metal-Organic Chemical Vapor Deposition
Authors: Biefeld R. M. , Allerman A. A. , Kurtz S. R. 
Published: April 2011

AbstractAlSb and AlAsxSb1−x epitaxial films grown by metal-organic chemical vapor deposition were successfully doped p- or n-type using diethylzinc or tetraethyltin, respectively. AlSb films were grown at 500°C and 76 torr using trimethylamine or ethyldimethylamine alane and triethylantimony. We examined the growth of AlAsSb using temperatures of 500 to 600 ° C, pressures of 65 to 630 torr, V/Ill ratios of 1–17, and growth rates of 0.3 to 2.7 μm/hour in a horizontal quartz reactor. SIMS showed C and 0 levels below 2 × 1018 cm−3 and 6×1018 cm−3 respectively for undoped AlSb. Similar levels of O were found in AlAs0.16Sb0.84 films but C levels were an order of magnitude less in undoped and Sn-doped AlAs0.16 Sb0.84 films. Hall measurements of AlAs0.16Sb0.84 showed hole concentrations between l×1017 cm−3 to 5×1018 cm−3 for Zn-doped material and electron concentrations in the low to mid 1018 cm−3 for Sndoped material. We have grown pseudomorphic InAs/InAsSb quantum well active regions on AlAsSb cladding layers. Photoluminescence of these layers has been observed up to 300 K.
W, WSix and Ti/Al Low Resistance Ohmic Contacts to InGaN, InN and InAlN
Authors: Vartuli C.B. , Pearton S.J. , Abernathy C.R. , MacKenzie J.D. , Shul R.J. , Zolper J.C. , Lovejoy M.L. , Baca A.G. , Hagerott-Crawford M. 
Published: April 2011

AbstractW, WSi0.44 and Ti/Al contacts were examined on n+ In0.65Ga0.35N, InN and In0.75Al0.25N. W was found to produce low specific contact resistance (Qc ˜ 10−7 Ω cm2) ohmic contacts to InGaN, with significant reaction between metal and semiconductor at 900 °C mainly due to out diffusion of In and N. WSix showed an as-deposited Qc of 4×10−7 Ω cm2 but this degraded significantly with subsequent annealing. Ti/Al contacts were stable to Ω 600 °C (Qc, ˜ 4×10−7 Ω cm2 at ≤600 °C). The surfaces of these contacts remain smooth to 800 °C for W and WSix and 650 °C for Ti/Al. InN contacted with W and Ti/Al produced ohmic contacts with Qc ˜ 10−7 Ω cm2 and for WSix Qc ˜ Ω cm2.All remained smooth to ˜ 600 °C, but exhibited significant interdiffusion of In, N, W and Ti respectively at higher temperatures. The contact resistances for all three metallization schemes were ≥ 10−4 Ω.cm2 on InAIN, and degrades with subsequent annealing. The Ti/Al was found to react with the InA1N above 400 °C, causing the contact resistance to increase rapidly. W and WSix proved to be more stable with Qc ˜ 10−2 and 10−3 Ω cm2 up to 650 °C and 700 °C respectively.
A Defect Map for Degradation of Ingaasp/Inp Long Wavelength Laser Diodes
Authors: Chu S.N.G. , Nakahara S. 
Published: April 2011

AbstractWe summarize the characteristic defect structures associated with gradual-degradation, rapiddegradation, catastrophic (mirror-facet) optical damage (COD), electric static discharge (ESD) and electric overstress (EOS) damages to provide a defect-map for device failure mode analysis. The generation mechanisms of these lattice defects are discussed which pinpoint the weak links in the device structures.
The 4f Intrashell Transitions of Ytterbium in Indium Phosphide
Authors: Maat-Gersdorf Ingrid De , Gregorkiewicz T. , Ammerlaan C. A. J. , Christianen P. C. M. , Maan J. C. 
Published: April 2011

AbstractZeeman measurements in magnetic fields up to 16 T have been performed on the no-phonon lines labelled #3, #4, and #8 of the spectrum of ytterbium impurities in indium phosphide. A strong polarization effect and changes in intensities were observed. An energy level diagram is presented that satisfactorily explains the magnetic field effect and the relative intensities of the photoluminescence lines and is consistent with experiments described in the literature.
Optical Anisotropy of Er Centers in GaAs:Er,O
Authors: Hogg R. A. , Takahei K. , Taguchi A. , Horikoshi Y. 
Published: April 2011

AbstractFor GaAs:Er,O the anisotropic photoluminescence (PL) properties of the Er-20 center and its preferential alignment within the GaAs matrix have been revealed by the polarization dependence of host-excited PL when detecting emission polarized along certain crystallographic directions. In the present paper, a polarized intra-4f-shell photoluminescence excitation (PLE) spectroscopic study of Er centers incorporated in GaAs is reported. This technique is not only sensitive to those centers which luminesce under host-excitation, but also to other Er centers incorporated in the host, thus allowing the polarized PL properties of most Er centers to be studied. A comparison of the polarization characterisitcs of host-excited PL and direct intra-4f-shell PLE, due to the difference in the excitation mechanisms, is made and the information which may be gained from such measurements is discussed. For the Er-20 center, we confirm the optical anisotropy and preferential alignment of the center previously observed in host-excited PL. Incorporation mechanisms for the Er-20 center which could result in the observed polarization dependence are discussed.
Incorporation, Excitation and De-Excitation of Erbium in Crystal Silicon
Authors: De Dood M. J. A. , Kik P. G. , Shin J. H. , Polman A. 
Published: April 2011

AbstractTemperature quenching of the 1.54 μm photoluminescence intensity and lifetime of Er in crystal Si was investigated between 12 K and 150 K. A p-type Czochralski-grown Si (100) wafer was doped with Er to a peak concentration of 5×1018 cm−3 using 1.5 MeV ion implantation. The Er doped layer was co-implanted with N to a peak concentration of 6×1019 N cm−3 The sample was annealed at 490 °C for 2 hours and at 600 °C for 1 hour. The 1.54 μm photoluminescence intensity shows a weak temperature quenching between 12 and 75 K, characterised by an activation energy of 1–10 meV. For temperatures above 75 K, a strong intensity quenching with an activation energy of 210 ± 10 meV is observed. The luminescence lifetime decreases from 420 μs at 12 K to 1 μs at 170 K, and shows strong quenching behaviour above 75 K, characterised by an activation energy of 135 ± 5 meV. The results are interpreted in terms of an impurity Auger energy transfer model. The lifetime quenching is attributed to a phonon assisted backtransfer process which becomes dominant at high temperatures. Intensity quenching is attributed to both the backtransfer process and a carrier de-trapping process which reduces the Er excitation rate. Spectral response measurements on Er implanted solar cells confirm the presence of a backtransfer process at room temperature.
Photoluminescence Kinetics Model of P-Type GaAs:Nd
Authors: Saha U. K. , Lozykowski H. J. 
Published: April 2011

AbstractIn this work we have developed a model for the kinetics of the energy transfer from the host lattice to the core states of rare earth (RE) centers. We have derived a set of kinetics differential equations of RE luminescence in p-type semiconductor. Numerically computed rise and decay time of RE luminescence as a function of excitation power shows good agreement with the experimental data obtained for p-type GaAs:Nd.
Erbium Doped Silicon for Light Emitting Devices
Authors: Michel J. , Zheng B. , Palm J. , Ouellette E. , Gan F. , Kimerling L. C. 
Published: April 2011

AbstractWe report on the excitation and de-excitation processes of erbium implanted in silicon and the integration of Si:Er light emitting devices (LED) with standard CMOS technology. We find two deexcitation processes, an Auger process below 100 K and a phonon mediated energy backtransfer above 100 K. We present the first optical voice link with a silicon LED as the emitter. Optical transmission system performance with our LED is possible below 200 K.
1.54 μm Photoluminescence and Electroluminescence in Erbium Implanted 6H SiC
Authors: Yoganathan M. , Choyke W. J. , Devaty R. P. , Pensl G. , Edmond J. A. 
Published: April 2011

AbstractPhotoluminescence in the neighborhood of 1.54μm due to the 4I13/2 → 4l15/2 transitions is observed from 2 K up to 520 K in erbium implanted 6H SiC. The integrated 1.54 μm photoluminescence (PL) intensity is almost constant from 2 K up to about 400 K, with slight sample to sample variation. The shallow nitrogen donors play an important role in the excitation of the Er3+ centers. 1.54 μm electroluminescence (EL) is observed in erbium implanted 6H SiC p-n junctions under forward bias conditions. The EL spectrum is identical to the PL spectrum.
Er-Doping of Gan and Related Alloys
Authors: Pearton S. J. , Abernathy C. R. , MacKenzie J. D. , Schwartz R. N. , Wilson R. G. , Zavada J. M. , Shul R. J. 
Published: April 2011

AbstractEr incorporation into GaN, AIN, MAIN and InGaN can be achieved using either direct ion implantation or by doping during Metal Organic Molecular Beam Epitaxy using metalorganic or elemental sources. When co-implanted with 0 and annealed between 600–800°C, strong luminescence at 1.54pm from optically excited Er3+ is detected in both binary nitrides and there was no measurable diffusion of Er in any of the materials. The low vapor pressures of the gaseous source compounds (erbium 2, 2, 2, 6-tetramethyl-3, 5-heptanedionate for Er + O; erbium bistrimethylsilylamide for Er) makes transport difficult unless high bubbler temperatures are used. Er concentrations up to ∼3×1021cm−3 in AIN have been obtained using a solid Er source. Microdisk laser structures with Er-doped active layers have been fabricated using a novel KOH selective wet etch and Cl2/CH4/H2/Ar dry etching.
Photoluminescence of Erbium-Diffused Silicon
Authors: Horiguchi H. , Kinone T. , Saito R. , Kimura T. , Ikoma T. 
Published: April 2011

AbstractErbium films are evaporated on crystalline silicon substrates and are thermally diffused into silicon in an Ar+02 or H2 flow. Very sharp Er3+-related luminescence peaks are observed around 1.54 μ m.The main peak as well as the fine structures of the luminescence spectra depend on the annealing atmosphere, suggesting different luminescence centers. The full width at half maximum (FWHM) of the main peaks is ≤ 0.5nm at 20K. Thermal diffusion with Al films on top of the Er films is found to increase the intensity of the Er3+-related peaks greatly. The temperature dependence between 20 K and room temperature is relatively small, and a strong luminescence is obtained at room temperature.
About the Electrical and Structural Properties of Erbium Thermally Diffused in Single Crystal Silicon
Authors: Binetti S. , Acciarri M. , Gelmi I. , Pizzini S. 
Published: April 2011

AbstractHaving preliminary confirmed the possibility of erbium doping by thermal diffusion, we have used this process to introduce erbium into a silicon substrate from metallic erbium or erbium oxide sources. Diffusion experiments were carried out at 1050, 1200 and 1250°C. The Er:Si diffused samples were investigated using four probe resistivity and thermopower techniques for the measure of the concentration and type of carriers, SIMS and Auger spectroscopy for chemical analysis of the diffused layers and photoluminescence (PL) measurements at temperatures ranging from 2 to 298 K for the detection of optical activity. None of the samples prepared presented measurable PL at 2 K, except for one single sample on top of which was deposited an erbium doped silica glass. The electrical properties, instead, were deeply influenced by doping, indicating the formation of both donor and acceptors.