A digital image processing system based on a charge-coupled device (CCD) camera interfaced to a Texas Instruments Professional Computer (TIPC) has been implemented on the Cameca IMS-3F Ion Microscope to improve lateral imaging capabilities. The CCD sensor, produced at TI, generates a 376 × 288 pixel image, and a hardware interface to the TIPC provides an 8-bit grayscale (256 levels) for subsequent storage and display. The Cameca ion microscope projects secondary ions from the sample onto a microchannel plate/fluorescent screen combination. The CCD array images the screen directly and no vacuum modifications to the Cameca are required. Nitrogen cooling of the CCD imager to reduce thermal noise allows low light levels to be integrated for several minutes and displayed on the TIPC, providing a substantial increase in sensitivity over the standard optics. False color imaging enhances the contrast of various features in the ion image to provide ease of identification. A variety of software options, such as frame mosaicking, multiple frame overlays, color threshold modification and histogram equalization are available. The TIPC has also been interfaced to the Cameca controlling computer to allow display of ion images during depth profiling.

This study is concerned with the fundamental limitations imposed by cascade mixing and recoil implantation on the depth resolution of secondary ion mass spectrometry (SIMS), and the effects of these limitations on the determination of impurity profiles in semiconductors.

We present experimental results of measurements on atomically, or near atomically abrupt impurity profiles in Si using magnetic sector (Cameca) and quadrupole (Atomica) SIMS machines. The analysis conditions and samples have been chosen to minimize instrument (crater wall resputtering) and surface (equilibration time) effects. Under such conditions the leading edge of an abrupt signal is smeared to a complimentary error function, while the trailing edge exhibits an exponential decay reminiscent of recoil implantation profiles.

Modifications of the Boltzmann Transport Equation (BTE) approach to ion implantation in multilayer targets will be shown to provide a first principles calculation of such SIMS knock-on phenomena, which is in good agreement with the empirical results.

The measurement technique for quantitative distribution analysis of P in the layer system SiO2/Si was optimized. Oxygen primary ions and an increased oxygen pressure ( 5.10E-5mbar) in the sample chamber were used for elimination of the matrix effect.A computer routine for precise adjustment of the mass spectrometer during depth profiling with high mass resolution was developed. Charging effects were compensated by flooding the sample with electrons, optimized biasing of the accelerating potential of the secondary ions and normalization to a reference signal. The improved measurement technique was used for determination of segregation coefficients which are used as input parameters for process modeling in MOS transistor production.

An improved method for the analysis of multi-exponential transients with high resolution has been applied to DLTS. Full-waveform fittings, using the technique of Modulating Functions, are made to digitized transients captured by a computer. This technique is described and results for both simulated data (with noise) and real data are shown. The advantages over previously published techniques in resolution, calculation speed, insensitivity to truncation error and noise are discussed. Also, how this method allows for a determination of the number of components is presented.

Deep level transient spectroscopy (DLTS), which assumes a single exponential decay form for the transient junction capacitance, is the most commonly used method to characterize deep impurity levels in semiconductors. However conventional DLTS may lead to erroneous results if there are several closely spaced energy levels or the emission rate has a continuous spectrum. To overcome this difficulty a novel method named the multi-exponential analysis of DLTS by CONTIN (MEDLTS by CONTIN) is proposed. This method analyzes the emission rate to have a finite continuous spectrum S(λ) which appears in the transient junction capacitance C(t)=, by using the program “CONTIN” developed by Provencher in biophysics. Even if S(λ) includes two peaks at λ1 and λ2, those peaks can be distinguished for λ2/ λ1>2. As an example of the application of this method, deep levels in Si:Au were experimentally investigated. According to the three dimensional S(λ)-T2/λ-1/T representation, the single peak in the conventional DLTS was clarified to consist of two adjacent levels with activation energies and capture cross sections EB1=0.51eV, σB1=4.0×10−15cm2 and EB2=0.47eV, σB2=1.1×10−15cm2. With the assumption of the finite continuous spectrum S(λ) for the emission rate, MEDLTS by CONTIN permits one to get much information correctly. MEDLTS by CONTIN is superior to the conventional DLTS because it is a single-temperature scan, multi-exponential analysis instead of the conventional multi-temperature scan, single-exponential analysis.

Defects in high-resistivity neutron transmutation doped (NTD) silicon without annealing were characterized by optical current DLTS with a bipolar rectangular weighting function using a GaAs LED. The DLTS method with a bipolar rectangular weighting function was also described. Two clear peaks labeled A and B were observed in addition to unresolved peaks due to overlaps of DLTS signals of several defects. The thermal emission activation energies of defects A and B were 0.15 and 0.50 eV, respectively. The DLTS signals of these defects were broader than the calculated ones. This indicates the clustered nature of defects produced by fast neutron irradiation. However, the fact that the characteristic peaks were observed suggests that the material state of high-resistivity NTD silicon is crystalline but not amorphous.

Using electrical and optical DLTS analysis based on the capacitance transient measurements and taking into account the spatially dependent capture and the competition between emission and capture, parameters of Titanium levels in silicon are derived. By curve fitting the calculation to trap-filling data, the electron capture cross section of the first donor level (Ec - .284 eV) is found to be 5.8 10-15 exp (.013/kT)cm2 at ξ= 5 104 V/cm. The hole trap capture cross section of the second donor level (Ev + .260 eV) is found to be 1.97 10-17exp (-.017/kT)cm2 at zero electric field.

Transient photoconductivity measurements with the time-resolved microwave conductivity (TRMC) method have been applied to three different types of semiconductors: hydrogenated amorphous silicon, single crystalline silicon and GaAs/GaAlAs multiple quantum well structures. Analysis of the signals in terms of charge carrier-lattice interaction points to an intimate relation between TRMC signals and intrinsic material properties. It is shown that the TRMC-technique is an excellent tool to characterize photosensitive materials.

A contactless spatially resolved measurement of bulk free-carrier lifetime in polycrystalline silicon ingots was accomplished using optically modulated free-carrier infrared absorption. Using a CW Nd:YAG laser (λ = 1.319 μm) for a probe and novel pulsed, tunable, infrared dye laser (λ = 1.10 to 1.13 μm) with photon energies near the Si bandgap, for a pump, the free-carrier lifetime was determined from transient absorption measurements to a maximum depth of 3.0 cm from the surface of an ingot. The spatial dependence of the free-carrier lifetime and the distribution of precipitates (determined from infrared probe transmission measurements) measured along the growth axis of an ingot were found to be strongly related to the spatial dependence of the I–V characteristics of large area solar cells fabricated from the subsequently wafered ingot.

This paper presents a non-destructive technique for characterizing The Defect Free Zone (DFZ) of silicon wafers. The method consists in measuring the decay of microwave reflection following the creation of excess carriers by a light pulse. For wafers with similar surface passivation we have found a direct correlation between the transient duration and the size of the DFZ. A computer model of the microwave reflection in silicon wafers with different size of DFZ agrees with experimental observation.

The defect microstructures of GaAs substrates have been investigated in a multi-technique approach including integral cathodoluminescence (CL), scanning electron acoustic microscopy (SEAM), double crystal x-ray topography (XRT), and defect delineation etch. The XRT, CL, and SEAM studies are of identical areas on<100> SI GaAs(Cr) grown by the liquid encapsulated Czochralski (LEC) method and by the horizontal Bridgman (HB) method. Correlation was made to the defect structure revealed by defect delineation etching. The samples were also characterized by Fourier transform photoluminescence (FTPL) to qualitatively identify the major transitions contributing to the CL images. The CL, SEAM, XRT, and defect delineation etch images of each material are compared and their different perspectives are discussed.

The pattern and density of dislocations in GaAs is thought to affect the ultimate performance of finished devices. Previous studies of dislocation networks have usually involved molten KOK etching of GaAs wafers or X-ray topography. A relatively new technique, Thermal Wave Microscopy (TWM), offers an alternative method of analysis. High frequency blanking of the scanning electron beam in an SEM produces thermal waves that propagate approximately 1–2 wavelength through a sample, are then carried by thermoacoustic waves and detected by a piezoelectric transducer. Dislocations, microcracks, and voids will disturb this wave and the resulting image will show a change in contrast (bright or dark) at the defect site. Resolution is dependent on the thermal properties of the material being analyzed as well as on the accelerating voltage, beam current, beam blanking frequency and phase of the electron beam. TWMim ages of dislocation networks in as-received GaAs are very similar in appearance to the results of molten KOH etching. TWM is a relatively new technique for microanalysis. Its full range of applications are still being explored. For determination of dislocation networks it is a faster, less cumbersome method of analysis. TWM is a basically nondestructive technique involving none of the uncertainties of molten KOH etching (etch time, etch uniformity). For this reason TWM is recommended as an alternative analytical technique.

The measurement of single-crystal elastic properties is an important method of materials characterization. Elastic properties define intrinsically bulk behavior, but they also provide a microscopic insight into the dynamical behavior of the crystal lattice in relation to crystal structure and bonding. Moreover, they are particularly informative probes into the onset and the nature of a lattice instability and its role in inducing a phase transformation. On a macroscopic scale, stress-strain relationships, particularly those of an anisotropic kind, can be better understood and described in terms of the single-crystal elastic constants.

The hyperfine interaction between electronic and nuclear spins in hydrogenated amorphous silicon has been observed for the various paramagnetic defects in this material by electron spin resonance (ESR) and electron nuclear double resonance (ENDOR). The large hyperfine interaction between dangling bonds and 29Si as well as between donor electrons and 31p or 75 As nuclei can be resolved in ESR and provides direct information about the structure of the underlying electronic states. The smaller dipolar coupling of all paramagnetic states to more distant nuclei leads to an ENDOR response near the free nuclear resonance frequencies, which can be used to study the coupling of the electronic and nuclear spin system to the lattice phonons and to each other.

Thermal neutrons are captured by several elements which emit charged particles as reaction products. These particles leave etchable damage tracks in detector materials placed against a sample, creating a map of the distribution and concentration of the target element. The most common applications are for trace U using fission fragment tracks and B using alpha tracks. Li, N and possibly S and O can also be determined. We have applied the technique to B in metals and coatings, Li in Al, N in glass and U in O-ring seals. Dectection limits are better than 10−11g/g for U, 10−9g/g for B, 10−6 g/g for Li and 0.1 wt % for N. Spatial resolution for mapping is about 25 μm.

Diffuse neutron or x-ray scattering close to the Bragg peaks (Huang scattering) and far away from Bragg peaks (Zwischenreflex-scattering) supplies detailed information on point defects and small agglomerates in crystals [1]. The defect structure, i.e. the lattice location, the displacements of the near neighbours and the strength and symmetry of the long ranged displacement field can be determined. In order to demonstrate the power of this technique, we report on recent experimental results. Interstitially dissolved N and O in Nb are located on octahedral sites and create rather large displacements in their vicinity. Their long ranged displacement field shows the symmetry of the defect site. The light interstitials H and D in Nb are located on tetrahedral sites and their long ranged displacement field shows the symmetry of the host lattice. A rather complicated defect model is necessary in order to explain the local defect structure.