This paper reports on capacitance measurements on Czochralski-grown and float-zone silicon subjected to oxygen implantation, subsequent neutron irradiation and finally high pressure thermal anneals. The purpose of this work was the study of the effect of irradiation on the formation of thermal donors in silicon. The observed changes in the C-V characteristic curves and profiles are discussed. We found that oxygen-ion implantation followed by neutron irradiation results in shallow and deep level acceptor-like defects formation. Prolonged heat treatment leads to thermal donor generation as usual in Cz-Si annealed at 450 °C. The most striking result of the study is finding that high pressure thermal anneals result in extra donor formation. The effects mentioned above may lead to changes in the type of conductivity depending on oxygen content in the material, hydrostatic pressure and an extent of damage caused by the irradiation.

The effect of aluminum gettering on different silicon materials used for solar cells has been investigated by means of microwave photoconductivity decay (μ-PCD) and electron beam induced current (EBIC). μ-PCD measurement revealed that the lifetime of multicrystalline silicon (mc-Si) with a lower initial lifetime could be increased by high temperature gettering (1000 °C), while that of mc-Si with a higher initial lifetime could not be increased, but was even degraded. EBIC results revealed that no significant improvement of diffusion length was observed in both contaminated and uncontaminated wafers, while 850 °C Al gettering was employed. It is concluded that both the initial material quality and the thermal treatment have influences on the effect of Al gettering. In addition, dislocations with bright EBIC contrast were discovered in annealed mc-Si wafers, the origin of which is discussed.

This paper is addressed to the discussion of the effect of the dislocation structure and the impurity contamination on the photoluminescence of Czochralski (Cz) silicon in the range of the D1 emission at 0.8 eV. Two types of dislocation systems were considered. One consists of intersecting hexagonal half loops of screw and 60° segments. The other one consists of a set of non-intersecting, parallel 60° dislocations. In both cases the plastic deformation processes were carried out at 670 °C, taking care to avoid unwanted impurity contamination. It is shown that the PL emission of pure 60° dislocations in the D1 region is missing the 0.807 eV component and consists of a narrow band at 0.817 eV superimposed onto a broad background centered at 0.830 eV. It is also shown that a system of intersecting half loops presents both the 0.807 eV and the 0.817 eV components. The effect of thermal annealing at 800 °C was shown to induce oxygen precipitation effects, revealed by supplementary spectral features. It is eventually demonstrated that the set up of the D1 band is not necessarily connected with the contamination of 60° dislocations with metallic impurities. The major role of oxygen on the dislocation luminescence is eventually experimentally confirmed.

Diborane and hydrogen ions were co-implanted into silicon using an implanter without an ion analyzer. The samples were annealed at 1000 °C for 30 min in argon atmosphere. Regions containing carriers became narrower with an increasing fraction of H2 gas in the source mixed gas: for example, carriers were limited only in a narrow region from the surface to $0.3\;\mu$m on silicon implanted with a mixed gas of 57% H2–43% B2H6. The width of the region containing carriers was approximately double that ($\sim 0.6\;\mu$m) on B-implanted silicon. On the other hand, the width of the region containing B atoms on the H2 and B2H6 co-implanted silicon were slightly narrower than that on B-implanted silicon. The region containing inactivated B atoms had a large number of defects and small crystallites.

Electrical properties of the shallow thermal donors (TDs) in n-type CZ-Si diodes by the electron irradiation were investigated. After the electron irradiation, carrier concentration was decreased. From deep level transient spectroscopy (DLTS) measurements, some peaks related to TDs and vacancy-oxygen complexes were observed for the irradiated samples. The peak related to V-O and/or A-center at EC-0.18 eV increased with the electron fluence. To compare that, the level of EC-0.09 eV related to TDs was independent of electron fluence. In addition to that, reverse current of the diodes was increased with increasing irradiated electron fluence.

Using deep level transient spectroscopy (DLTS) measurements with zero-bias and reverse-bias cooling, we have observed new metastable defects (EM1, EM2 and EM3) in n-type silicon by hydrogen implantation at temperature as low as 88 K. We have investigated the trap parameters of these metastable defects and their concentration depth profiles. Hydrogen ion implantation was performed with energies of 80 keV, 90 keV, and 100 keV to a dose of 2 × 1010 cm−2. The silicon substrate temperature was kept at as low as 88 K during hydrogen implantation and then was raised naturally to room temperature. From analysis of Arrhenius plots, the energy levels of EM1, EM2 and EM3 are obtained to be Ec-0.29 eV, Ec-0.41 eV and Ec-0.55 eV, respectively. The depth profiles of metastable defects in 90-keV samples have a peak in the concentration around the depth of 0.68 µm, which is shallow compared with the projected range of 90 keV hydrogen. The peak position becomes deeper as the energy of ion implantation increases. This indicates that the production of metastable defects is caused by ion implantation. Additionally, comparison with helium-implanted samples suggests that implanted hydrogen is included in these metastable defects.

Cz-Si doped with boron was implanted at room temperature with 130 keV H2-ions at a high dose of 4×1016 cm−2. The specimens were annealed at a temperature of 450 °C for 10 h in argon ambient. High frequency (1 MHz) C-T and C-V measurements in the temperature range 80–400 K were carried out to study particular features of damage-related centres in the limit of a heavy damage. The presence of damage-related deep-level defects manifest themselves through several unusual features of C-T(V) curves. Sudden jumps of capacitance and hysteresis effects during sweeping temperature/voltage are unusual indeed and have been reported for the first time. Our experiments by filling and emptying deep-level defects with carriers by proper biasing diodes before the temperature/voltage sweep have revealed that the particular features are due to changes in the deep level occupation. The results presented give direct experimental evidence that the damage-induced deep-level defects themselves control the quasi-Fermi level position.

The thermoelectric power of silicon micro-samples grown by Czochralski method (Cz-Si) and annealed at 450 °C has been investigated at enhanced pressure up to 16 GPa. The correlation has been established between the thermoelectric power and pressure of the semiconductor-metal phase transition, on the one hand, and mechanical properties (microhardness, compressibility), on the other, for Cz-Si with different content of oxygen. Possible application of the studied properties for micro-device technology is discussed.

The influence of the laser annealing on the defect structure of the near-surface layer of silicon crystal implanted with 40 keV Ge ions is reported. Evolution of defect structure during nanosecond pulse laser annealing is characterised by means of several complementary methods: reflection high-energy electron diffraction, interference-polarizing microscopy, Rutherford back-scattering and secondary ion mass spectrometry. Regions irradiated with different energy densities of the laser beam are compared. The role of the dopant in the layer recrystallised from the melt is discussed.

Birefringence induced by crystal defects has been successfully characterized as standard ingot form in Si crystals by using a scanning infrared polariscope. It is found that there is a certain amount of defect-induced birefringence besides the birefringence due to the optical anisotropy in CZ Si crystals. If the infrared probing light is introduced to the crystallographic $\langle100\rangle$ directions, then the defect-induced birefringence is clearly observed with no influence of the optical anisotropy in cubic crystals. Although it is difficult to evaluate the absolute value of crystal defects, it is demonstrated that the SIRP measurement is very useful to nondestructively characterize the quality of Si crystals as standard ingot form without any special treatment.

Spatial distribution and properties of oxide were examined in 300 mm nitrogen (N) doped CZ-Si. Experimentally grown materials with N ranging from ~ 1013 cm−3 to 1015 cm−3 were studied by infrared light scattering tomography, scanning infrared microscopy, transmission electron microscopy and electron beam induced current. It was established that an increasing N content improves the uniformity of the radial distribution of precipitates in the bulk of the wafer, the density of precipitates reaching a level of ~ 109 cm−3. The width of the denuded zone varies in the range from $15\;\mu$m to $70\;\mu$m depending on radial position and N doping level. Electron microscopy revealed lower oxide precipitate densities of about 105 to 108 cm−3. The results are interpreted in terms of existence of agglomerates of nanometer size precipitate nuclei and/or by the defect-induced strain relaxation around the precipitates.


The stability of B atom near the Si(100)/SiO2 interface during annealing is studied by using ab initio calculation to investigate the atomic scale mechanism of B segregation at the Si(100)/SiO2 interface. Contrary to the experimental observations showing that B atoms segregate into SiO2, B atoms are found to be stable in Si free of defects. But authors can rephrase differently this sentence. On the other hand, when an O vacancy exists in SiO2, the B atom is trapped by the O vacancy and becomes quite stable in SiO2.

Deep defects in annealed InP have been investigated by deep level transient capacitance spectroscopy (DLTS), photo induced current transient spectroscopy (PICTS) and thermally stimulated current spectroscopy (TSC). Both DLTS results of annealed semiconducting InP and PICTS and TSC results of annealed semi-insulating InP indicate that InP annealed in phosphorus ambient has five defects, while InP annealed in iron phosphide ambient has two defects. Such a defect formation phenomenon is explained in terms of defect suppression by the iron atom diffusion process. The correlation of the defects and the nature of the defects in annealed InP are discussed based on the results.

Laplace transform photoinduced transient spectroscopy (LTPITS) has been applied to study defect centres in Fe-doped and undoped semi-insulating (SI) InP. A high resistivity (~ 2 × 107 Ω cm) of the latter was achieved by annealing at 950 °C for 40 h under a phosphorus overpressure. It is shown that shallow donors in this material have an activation energy of 10 meV and are mainly compensated with deep acceptors characterised by activation energies of 350 and 470 meV with respect to the bottom of the conduction band. In the Fe-doped material, the shallow donors are compensated with Fe-related deep acceptors having activation energies of 590 and 640 meV.

Photoluminescence and electrical measurements were carried out for studying the influence of rare-earth elements (Yb) concentration in the Ga melt on the electronic and structural properties of LPE GaAs epilayers. It was shown that at low concentration the main role of Yb is the gettering of residual impurities in the melt. At the same time, Yb addition in the melt changes the heterogeneous equilibrium by changing the stoichiometry of epilayers (increase of $V_{\text{Ga}}$). But at further increase of Yb concentration in the melt Yb begins to enter in the Ga-sublattice and cluster with deviation from the stoichiometry. An optimum concentration of Yb exists at which high-purity and stoichiometric epilayers for a device application can be obtained.

A non-degenerate four-wave mixing technique has been applied to investigate carrier transport and recombination in heavily C-doped GaAs embedded in a double-heterostructure. The carriers were injected into the 1 µm-thick p-GaAs layer via the 50 nm-thick barrier of AlGaAs:C or InGaP:Si, using the light interference pattern of two picosecond laser pulses at 532 nm. The dependence of the nonequilibrium carrier grating decay time on the grating period allows the determination of minority carrier diffusion coefficients: D = 35 cm2/s for p-GaAs ($p_0 = 2 \times 10^{19}$ cm−3) with AlGaAs barriers and D = 27 cm2/s for p-GaAs ($p_{0} = 1 \times 10^{19}$ cm−3) with InGaP barriers. This increase of electron mobility at the higher doping level was found to be in agreement with the decreasing role of carrier-carrier scattering in heavily-doped p-GaAs. The fast recombination of nonequilibrium carriers in the vicinity of a front barrier layer was evident and more pronounced for an AlGaAs than for an InGaP barrier.

Low-frequency current oscillation (LFO) in semi-insulating (SI) GaAs has been precisely measured with the guard-ring method using three electrodes, in which the electric field is well defined and controlled, and furthermore the surface leakage current becomes low. It is found from the precise measurements of I-V characteristics, waveforms and frequencies of LFO that the LFO phenomenon is well explained by the electric field-enhanced electron capture model taking into account the ionized EL2 concentration. The temperature dependences of LFO are also quantitatively explained by the model.


The defects in InP epitaxial structures (containing in part Pt nanoparticles) and SiGe/Si heterostructures, and their electrical behaviour are studied. In InP structures pinholes, in SiGe/Si structures misfit dislocations were observed in the epitaxial layers. These defects yielded different anomalies of the electrical behaviour, as excess and leakage currents, instabilities, anomalous temperature dependence and anomalous apparent barrier height. It is shown that inspite of anomalies, the electrical measurements provide useful and reliable information about the structures.

This paper reports on first results obtained on GaN epitaxial layer grown on a single wafer with a lateral variation in defect density. The chemically homogeneous GaN epitaxial layer was deposited by metalorganic chemical vapour deposition onto a specially prepared buffer layer. A chemical gradient in the nitrogen contents of the precursor flux was induced during the growth of the GaN buffer layer. This condition leads a corresponding gradient of the dislocation density within the epilayer. The electrical and optical properties of the GaN epilayer have been analysed by means of electron beam induced current, photoluminescence and photocurrent techniques. All our measurements reveal lateral gradients in the epilayer properties as concern (i) the density of recombining centres in the GaN film and (ii) their recombination activity, both radiative and nonradiative. This paper shows that a proper combination of beam based techniques can contribute to the detailed analysis of the well know yellow luminescence band which in the GaN epilayer here investigated consist of four well distinct peaks.

High purity InP crystals were grown by liquid encapsulated Czochralski method from undoped InP melt. Wafers from the grown crystals were annealed in phosphorus ambient for 95 hours at 950 °C and cooled slowly. Conversion to semi-insulating state by annealing was studied by temperature dependent Hall measurements and low temperature optical absorption spectroscopy.