Zhu Peiran

Damage accumulation and amorphization in GaAs by MeV Si+ ion implantation at different tilt angles☆

Abstract Damage accumulation and amorphization in GaAs(100) by MeV Si+ ion implantation at different tilt angles have been studied using the Rutherford backscattering and channeling technique. It was found that the total amount of damage increases linearly with the implant dose at doses less than the threshold dose for amorphization. Layer by layer amorphization was observed at doses higher than the threshold dose. The damage distribution is strongly influenced by the target tilt angle. With an increase in the implant tilt angle, the damage level decreases. A model for the damage accumulation and amorphization is discussed.

MEV PROTON ELASTIC BACKSCATTERING ANALYSIS OF SILICON-NITRIDE AND OXIDE LAYERS ON SILICON

A simple method for the analysis of concentration ratios N/Si and O/Si in silicon nitride and oxide layers on silicon substrate is presented. 1.95-MeV proton elastic backscattering was used to determine the composition and density. A comparison with 2.1-MeV helium Rutherford backscattering measurements is given. Results are in good agreement with each other. The method is especially useful to analyze samples of 20 000 angstrom or thicker layers. We conclude that these two techniques are complementary for the measurements of samples with different thickness. A brief discussion has been given on results.

THE ELASTIC RECOIL DETECTION BY C-IONS FOR HYDROGEN PROFILING IN SOLIDS

Abstract The depth profiling of hydrogen in solids has been performed by elastic recoil detection (ERD) with multicharged C ions at a small 1.7 MV tandem accelerator. Both experimental and theoretical analyses show a depth resolution of about 15–25 nm in the near surface region of solids. Optimization of the experimental parameters such as scattering geometry and incident beam energy has been performed by computer simulation.

Depth profiles of fluorine in 19F+ ion-implanted Pb1−xSnxTe and CdTe

The 19F(p,αγ)16O resonance nuclear reaction at 872.1 keV, with Γ = 4.2 keV was used to measure the depth profiles of fluorine in 19F+-implanted Pb1−xSnxTe and CdTe samples. A deconvolution procedure was performed to extract the depth profiles from the experimental excitation yield curves. The range parameters. Rp, ΔRp and SK, obtained in this experiment were compared with theoretical calculations.

RBS studies of the lattice damage caused by 1 Me V Si+ implantation into Al0.3Ga0.7As/GaAs superlattices at elevated temperature

The lattice damage accumulation in GaAs and Al0.3Ga0.7As/GaAs superlattices by 1 MeV Si+ irradiation at room temperature and 350-degrees-C has been studied. For irradiations at 350-degrees-C, at lower doses the samples were almost defect-free after irradiation, while a large density of accumulated defects was induced at a higher dose. The critical dose above which the damage accumulation is more efficient is estimated to be 2 x 10(15) Si/cm2 for GaAs, and is 5 x 10(15) Si/cm2 for Al0.8Ga0.7As/GaAs superlattice for implantation with 1.0 MeV Si ions at 350-degrees-C. The damage accumulation rate for 1 MeV Si ion implantation in Al0.3Ga0.7As/GaAs superlattice is less than that in GaAs.

Helium- and lithium-ion channeling in single crystals of silicon, zirconium dioxide, and strontium titanate

Abstract The channeling characteristics of 2.4 MeV helium and 4.2 MeV lithium ions in three types of monocrystalline targets (silicon, zirconium dioxide and strontium titanate) have been studied by means of Rutherford backscattering. Axial half angles ( Ψ 1 2 ) and minimum yields (χmin) have been measured and compared to theory. The observed “zero-depth” values of the axial half angles are smaller than theoretical predictions and χmin for Li and He ions in each sample is larger than the expected values. A brief discussion has been given on the results.

AXIAL CHANNELING STUDIES OF HETEROEPITAXIAL IN0.25GA0.75AS ON GAAS

Abstract Axial channeling results are presented for the analysis of the heteroepitaxial growth structure of In0.25Ga0.75As on GaAs by MBE. The strain measurements have utilized inclined-direction axial dechanneling and angular scans. Anomalously large dechanneling along the declined axis relative to the growth direction indicates the presence of lattice strain due to lattice mismatch. Imperfections or lattice defects in dislocation nature in the epitaxial layer also give rise to significant dechanneling.

Influences of H+ Implantation on the Boron-Doped Synthesized by Chemical Vapor Deposition Diamond Films

Diamond films (DF) were preliminarily B doped in situ during chemical vapor deposition. Subsequently, the films were implanted with 120 keV H+ to dose of 5 × 1014 ~ 5 × 1016cm-2. After the implantation, the B doped DF become insulating and Raman measurements indicate that the implantation has amorphous carbon and graphite etched. It is known that the formation of H-B pairs plays an important pole in property changes. However, for larger dose cases, the electrical resistance of DF is influenced by radiation damage and/or non-diamond phases. In addition to them, annealing makes the specimens conducting again. This phenomenon maybe has potential for application in designing DF device.

An overview of the ion beam laboratory at Beijing Institute of Physics

Abstract A multi-user MeV ion beam system has been installed and has been operating since 1983. It was used for research projects in various areas such as solid state physics, materials science and atomic physics. The operational characteristics and experiences, modifications, and end-station developments are discussed. The system is based on a small 2 × 1.7 MV Tandetron accelerator (General Ionex Corporation, USA) with a negative sputtering ion source and a home-made cold cathode Penning ion source with a charge-exchanger. Ions of almost all elements can be extracted with a large switching magnet to form three small angle beam lines. There are five beam lines installed. A summary of the beam lines that are being constructed for the activities of the laboratory will also be given. These include: Rutherford backscattering spectrometry (RBS), channeling analysis, particle-induced X-ray emission (PIXE), nuclear reaction analysis (NRA), elastic recoil detection analysis (ERDA), high-energy ion implantation (HEII). A proton microprobe, an atomic collision system for various optical measurements, and a cross-beam RBS-implantation end-station coupled with a 200 keV implanter are also installed in the laboratory.

MEV HE MICROBEAM ANALYSIS OF A SEMICONDUCTOR INTEGRATED-CIRCUIT

Abstract An MeV He + microbeam has been used to analyse a microscale semiconductor structure. The 2 MeV He + ion beam is limited to 25 μm diameter by a set of diaphragms and is further focused by quadrupole quadruplet to 3 μm diameter. The incident beam current on the sample is about 0.3 nA. The Rutherford backscattering (RBS) technique is applied to the measurement of the composition and depth profile in the near-surface region of a semiconductor integrated circuit.