Effects of Carbon-Ion Irradiation-Energies on the Molecular Beam Epitaxy of GaAs and Ingaas

1995 ◽  
Vol 388 ◽  
Author(s):  
Y. Makita ◽  
T. Iida ◽  
T. Shima ◽  
S. Kimura ◽  
A. Obara ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Current Density ◽  
Molecular Beam ◽  
Ion Irradiation ◽  
Hole Concentration ◽  
Ion Beam ◽  
High Energy ◽  
Beam Current Density ◽  
Carbon Ion ◽  
Activation Rate

AbstractCarbon ion (C+) irradiation during molecular beam epitaxy (MBE) growth of GaAs/GaAs and in0.53.Ga0.47As/InP layers was carried out using CIBMBE (combined ion beam and molecular beam epitaxy) method as a function of wide acceleration energy (Ea=30 eV-30 keV) at a constant ion beam current density. Judging from the monitored current density and the net hole concentration (INA-ND|) obtained from Hall effect measurements, activation rate as high as 88% was achieved for as-grown GaAs layers by C+ ion irradiation of Ea=~170eV. It was revealed that by annealing at 800°C, a slight enhancement (~ 10%) of INA-ND| is practiced for Ea <~ 130eV but a significant increase of INA-ND| is realized for Ea>~lkeV. IN in0.53Ga0.47As/InP layers with increasing Ea, a type conversion of electric conduction from n to p was found to occur at Ea= ~70~100eV. these observations describe that Ea plays a vital role to determine the location of incorporated electrical and optical active impurities in GaAs and inGaAs. Further for comparison, C+-implanted GaAs layers were prepared by high-energy (400 keV) ion-implantation as a function of substrate temperature (T1=RT-600 °C). For C dose concentration of lxl018cm-3\ the highest activation rate of ~20 % was obtained at T1=~150 °C. This result states that CIBMBE method is a superior doping method in view of activation rate of introduced dopants and the formation of damage-free ion-irradiated layers.

Low temperature photoluminescence from GaAs impinged by mass-separated low-energy C+ ion beams during molecular beam epitaxy

1993 ◽  
Vol 316 ◽  
Author(s):  
Tsutomu Iida ◽  
Yunosuke Makita ◽  
Stefan Winter ◽  
Shinji Kimura ◽  
Yushin Tsai ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Low Temperature ◽  
Molecular Beam ◽  
Hole Concentration ◽  
Ion Beam ◽  
Ion Beams ◽  
Beam Current Density ◽  
Molecular Beam Epitaxy Growth ◽  
Spectral Evolution ◽  
Activation Rate

ABSTRACTC-doped GaAs films were prepared by novely a developed, combined ion beam and molecular beam method (CIBMBE) as a function of hyperthermal (30–500 eV) energies (EC+) of carbon ion (C+) beam. Ion beams of a fixed beam current density were impinged during molecular beam epitaxy growth of GaAs at substrate temperature of 550 °C. Low temperature (2 K) photoluminescence (PL) has been used to characterize the samples together with Hall effects measurements at room temperature. Through the spectral evolution of an emission denoted by [g-g]β which is a specific emission relevant to acceptor-acceptor pairs, the activation rate was confirmed to increase with increasing EC+ for EC+ lower than 170 eV. It was explicitly demonstrated that the most effective Ec+ to establish highest activation rate is located at ~170 eV. This growing activation rate was suggested to be attributed to the enhanced migration of both impinged C and host constituent atoms with increasing EC+. This surmise was supported also by Hall effect measurements which revealed the maximum net hole concentration ( |NA-ND| ) for EC+=170 eV. For EC+ higher than ~170 eV, increasing EC+ was found to induce the reduction of activation rate. It was suggested that this observation is ascribed not to the formation of C donors but to the enhanced sputtering effect of impinged C+ ions with increasing EC+.

Damage-Free Ion Beam Doping of Carbon During Molecular Beam Epitaxy of GaAs

1993 ◽  
Vol 316 ◽  
Author(s):  
Yunosuke Makita ◽  
Tsutomu Iida ◽  
Shinji Kimura ◽  
Stefan Winter ◽  
Akimasa Yamada ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Hole Concentration ◽  
Ion Beam ◽  
Energy Shift ◽  
Beam Current ◽  
High Energy ◽  
Carbon Doping ◽  
High Mass ◽  
Impurity Effects

ABSTRACTRecently, we introduced various acceptor impurities into MBE-grown ultra-pure GaAs by conventional high-energy ion implantation and found many novel shallow emissions associated with acceptor-acceptor pairs. Most of these emissions were easily quenched by extremely small amount of residual donor atoms which were unintentionally introduced during doping processes. For the interpretation of impurity effects, the usage of mass-separated atom as dopant source was strongly suggested. Along this consideration, we developed combined ion beam and molecular beam epitaxy (CIBMBE) technology, in which damage-free doping with high mass purity (M/ΔM=100) is expected to be possible. We here present the results of low-energy (100 eV) carbon ion doping using CIBMBE method. Samples were prepared asa function of growth temperature (Tg=400-700°C) and ion beam current. Net hole concentration, |NA-ND| as high as ~1×1020 cm-3 was obtained in as-grown samples. In 2K photoluminescence spectra, emissions due to acceptor-acceptor pairs exhibit specific energy shift with growing |NA-ND|. Results indicate that carbon doping can be made efficiently even at Tg as low as 500°C without any post heat treatment. These results also tell that by CIBMBE method no serious radiation damages are produced and the undesired impurity contamination can be considerably suppressed.

Growth of Ge1-xCx Alloys on Si by Combined Low-Energy Ion Beam and Molecular Beam Epitaxy Method

1996 ◽  
Vol 438 ◽  
Author(s):  
H. Shibata ◽  
S. Kimura ◽  
P. Fons ◽  
A. Yamada ◽  
Y. Makita ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Ion Irradiation ◽  
Ion Beam ◽  
Low Energy ◽  
Irradiation Damage ◽  
Molecular Beam Epitaxy Method ◽  
Deposited Films ◽  
Very High

AbstractA combined ion beam and molecular beam epitaxy (CIBMBE) method was applied for the deposition of a Ge1-xCx alloy on Si(100) using a low-energy ( 50 – 100 eV ) C+ ion beam and a Ge molecular beam. Metastable Ge1-xCx solid solutions were formed up to x = 0.047, and the CIBMBE method was shown to have a very high potential to grow metastable Ge1-x,Cx alloys. It was also revealed that the sticking coefficient of C+ ions into Ge was ∼28% for Ei, = 100 eV and ∼18% for Ei = 50 eV. Structural characterization suggests that the deposited films are single crystals grown epitaxially on the substrate with twins on {111} planes. Characterization of lattice dynamics using Raman spectroscopy suggested that the deposited layers have a small amount of ion irradiation damage.

Effects of High-Energy Carbon Ion Irradiation on Isatis Indigotica Fort

2011 ◽  
Vol 317-319 ◽  
pp. 2056-2062 ◽  
Author(s):  
Guang Liang Shi ◽  
Xue Hong Wang ◽  
Kai Guo ◽  
Zhao Zhou Li ◽  
Xiao Yan Hu ◽  
...  
Keyword(s):  
Soluble Protein ◽  
Selective Breeding ◽  
Ion Irradiation ◽  
Ion Beam ◽  
High Energy ◽  
Total Soluble Protein ◽  
High Dose ◽  
Isatis Indigotica ◽  
Carbon Ion ◽  
Different Doses

The aim of this study was to provide a theoretical basis for a high-energy carbon ion irradiation process for inducing mutations for selective breeding in Isatis indigotica Fort. The experiments were designed to evaluate the effects of different doses of high-energy 12C6+ ions (10-140 Gy) on physiological changes in I. indigotica seedlings. Dry seeds of I. indigotica were irradiated using different doses of 270 MeV energy 12C6+ ion beam, and the response of the subsequent seedlings was monitored using well-established indexes of physiological characteristics. Results showed that optimum results were achieved with a high-dose 12C6+ ion beam at 35 Gy where the activities of superoxide dismutase (SOD) and catalase (CAT) were enhanced. However, excessive irradiation reduced the activities of SOD and CAT. As the dose increased, the activity of peroxidase increased initially and then decreased compared with controls that were not irradiated (0 Gy). The content of malondialdehyde first decreased and then increased with the treatment. Total soluble protein content initially increased and then decreased with increasing doses of radiation; the proline content improved sharply compared to the control. The results of this study suggest that that a low dose of 12C6+ ion beam could enhance the activities of protective enzymes and the levels of proline and soluble protein, and that a dose range of 35–60 Gy is likely to be optimum for inducing useful mutations in I. indigotica for a stable selective breeding program.

Argon Ion Bombardment During Molecular Beam Epitaxy of Ge (001)

1988 ◽  
Vol 128 ◽  
Author(s):  
Eric Chason ◽  
K. M. Horn ◽  
J. Y. Tsao ◽  
S. T. Picraux
Keyword(s):  
Molecular Beam Epitaxy ◽  
Surface Morphology ◽  
Molecular Beam ◽  
Ion Beam ◽  
High Energy ◽  
Low Energy ◽  
High Energy Electron ◽  
Argon Ion Bombardment ◽  
Argon Ion

ABSTRACTUsing in situ, real-time reflection high energy electron diffraction (RHEED), we have measured the evolution of Ge (001) surface morphology during simultaneous molecular beam epitaxy and Ar ion beam bombardment. Surprisingly, low-energy Ar ions during growth tend to smoothen the surface. Bombardment by the ion beam without growth roughens the surface, but the surface can be reversibly smoothened by restoring the growth beam. We have measured the effect of such “ion beam growth smoothening” above and below the critical temperature for intrinsic growth roughening. At all measured growth temperatures the surface initially smoothens, but below the critical roughening temperature the final surface morphology is rough whereas above this temperature the final morphology is smooth.

scholarly journals Effects of ion-beam irradiation on the L10 phase transformation and their magnetic properties of FePt and PtMn films (Invited)

2005 ◽  
Vol 887 ◽  
Author(s):  
Chih-Haung Lai ◽  
Sheng-Huang Huang ◽  
Cheng-Han Yang ◽  
C.C. Chiang ◽  
S. H. Liou ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Current Density ◽  
Ion Irradiation ◽  
Ion Beam ◽  
Beam Current ◽  
Spin Valves ◽  
Beam Current Density ◽  
High Coercivity ◽  
Beam Irradiation ◽  
Ion Beam Irradiation

ABSTRACTIon-beam irradiation shows enhancement or degradation of magnetic properties on L10 phase of FePt and PtMn films. A highly ordered L10 FePt phase was directly achieved by using 2 MeV He-ion irradiation without conventional postannealing. The in-plane coercivity greater than 5700 Oe can be obtained after disordered FePt films were irradiated at the beam current of several μA/cm2 with the ion does of 2.4×1016 ions/cm2. The high beam-current-density results in direct beam heating on samples. In addition, the irradiation-induced heating process provides efficient microscopic energy transfer and creates excess point defects, which significantly enhances the diffusion and promotes the formation of the ordered phase. Consequently, the direct ordering of FePt took place by using ion-irradiation heating at temperature as low as 230°C. The comparison has been made on the [Fe/Pt]10/C films by RTA and high current-density He irradiation. Although RTA and ion irradiation both reach high coercivity, ion irradiation seems to suppress the (001) texture, leading to isotropic Hc. Ion-beam irradiation can also be applied to the transformation of PtMn. An ordered PtMn phase, a large exchange field and a high GMR ratio (11%) were obtained in PtMn-based spin valves by using 1.25 μA/cm2 He-ions. On the other hand, Ge-ion and O-ion irradiation completely destroyed the ferromagnetism of FePt and GMR of PtMn-based spin valves, respectively. We propose a novel approach to achieve magnetic patterning by using ion irradiation, which can be applied for patterned media and magnetic sensors.

Growth of Ge1−xCx, Alloys on Si by Combined Low-Energy Ion Beam and Molecular Beam Epitaxy Method

1996 ◽  
Vol 439 ◽  
Author(s):  
H. Shibata ◽  
S. Kimura ◽  
P. Fons ◽  
A. Yamada ◽  
Y. Makita ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Ion Irradiation ◽  
Ion Beam ◽  
Low Energy ◽  
Irradiation Damage ◽  
Molecular Beam Epitaxy Method ◽  
Deposited Films ◽  
Very High

AbstractA combined ion beam and molecular beam epitaxy (CIBMBE) method was applied for the deposition of a Ge1−x, Cx, alloy on Si(100) using a low-energy ( 50 – 100 eV ) C+ ion beam and a Ge molecular beam. Metastable Ge1−xCx solid solutions were formed up to x= 0.047, and the CIBMBE method was shown to have a very high potential to grow metastable Ge1−xCx alloys. It was also revealed that the sticking coefficient of C+ ions into Ge was ˜28% for Ei = 100 eV and ˜18% for Ei. = 50 eV. Structural characterization suggests that the deposited films are single crystals grown epitaxially on the substrate with twins on {111} planes. Characterization of lattice dynamics using Raman spectroscopy suggested that the deposited layers have a small amount of ion irradiation damage.

Electron and ion irradiation-induced dissolution of mechanical twins in the intermetalic U3Si: An in situ HVEM study

1989 ◽  
Vol 47 ◽  
pp. 652-653
Author(s):  
Charles W. Allen ◽  
Robert C. Birtcher
Keyword(s):  
Elevated Temperatures ◽  
Ion Irradiation ◽  
Ion Beam ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Heavy Ion ◽  
High Energy ◽  
Mechanical Twinning ◽  
In Situ Experiments

The uranium silicides, including U3Si, are under study as candidate low enrichment nuclear fuels. Ion beam simulations of the in-reactor behavior of such materials are performed because a similar damage structure can be produced in hours by energetic heavy ions which requires years in actual reactor tests. This contribution treats one aspect of the microstructural behavior of U3Si under high energy electron irradiation and low dose energetic heavy ion irradiation and is based on in situ experiments, performed at the HVEM-Tandem User Facility at Argonne National Laboratory. This Facility interfaces a 2 MV Tandem ion accelerator and a 0.6 MV ion implanter to a 1.2 MeV AEI high voltage electron microscope, which allows a wide variety of in situ ion beam experiments to be performed with simultaneous irradiation and electron microscopy or diffraction.At elevated temperatures, U3Si exhibits the ordered AuCu3 structure. On cooling below 1058 K, the intermetallic transforms, evidently martensitically, to a body-centered tetragonal structure (alternatively, the structure may be described as face-centered tetragonal, which would be fcc except for a 1 pet tetragonal distortion). Mechanical twinning accompanies the transformation; however, diferences between electron diffraction patterns from twinned and non-twinned martensite plates could not be distinguished.

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