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Deep-level transient spectroscopy (DLTS) and capacitance versus voltage measurements were used to study an influence of deep-level defects on electrical parameters of Yb–Al co-doped GaAs:Sn grown by liquid-phase epitaxy. DLTS spectra revealed the presence of several hole traps. Some of them were attributed to transition metals and native defects, respectively, which were commonly observed in as-grown material. It was found that increasing Yb caused a decrease in free carrier concentration. However, it was accompanied by an increase in the hole trap concentrations. On the other hand, adding Al resulted in a strong decrease in both the free carriers and the hole traps. The fact that deep levels may behave in this manner after adding Yb and Al into the Ga melt is an important factor to consider when interpreting changes in electrical parameters of the material.

Deep electronic states associated with iron silicide precipitates have been studied by means of deep-level transient spectroscopy. The observed spectra show the characteristic features of bandlike states at extended defects. From the stability of the states on annealing at moderate temperature they are tentatively attributed to precipitate-matrix interfaces.

High-resolution photoinduced transient spectroscopy (HRPITS) has been used to investigate defect centres in n-type epitaxial silicon after 24 GeV/c proton irradiation with fluences of 3×1014 and 9×1014 cm−2 followed by a long-term annealing at 80 oC. The measurements revealed nine traps with activation energies ranging from 5 to 460 meV. In the material irradiated with the lower fluence the concentration of V2O−/0 complexes is found to be approximately 4 times lower than that of divacancies V2−/0. After the irradiation with the higher fluence the material defect structure is different and the concentration of V2O−/0 complexes is around 6 times higher compared to that of divacancies V2−/0.

The Franklin Institute, Philadelphia, Pennsylvania, awarded the 2004 Benjamin Franklin Medal in Chemistry to Harry B. Gray for his pioneering contributions in the field of electron transfer in metalloproteins. In a series of elegant and challenging experiments beginning in the late 70s, Gray and his coworkers have shown that the transfer of electrons in metalloproteins can proceed over long distances (~ 20 A) and at fast rates. These experiments have involved the regiospecific functionalization of structurally characterized electron transfer proteins with ruthenium complexes, coupled with laser excitation and transient spectroscopy. Probing the effects of thermodynamic driving force, temperature, donor–acceptor distance and electronic coupling, Gray has shaped our detailed current understanding of the principles governing biological electron flow. The mechanism of electron transfer has been identified as electron tunneling mediated by the molecules separating donor and acceptor. Tunneling timetables have been established for various intervening media. Important biological processes like respiration and photosynthesis depend on facile electron transfer, and Gray's contribution serves as the fundamental basis for understanding these and many related reactions.

In this paper, static measurements and defect analysis performed on InAlAs/InGaAs/InP HFETs are presented. I d – V ds – T , I d – V gs – T and I g – V gs – T characteristics show anomalies (leakage current, degradation in saturation current, kink effect, distortions on I d – V d characteristics in saturation region after high voltage application, …). Deep defects analysis performed by means of capacitance transient spectroscopy (C-DLTS) and frequency dispersion of the output conductance ( G ds ( f )) prove the presence of deep defects with activation energies ranging from 0.12 to 0.75 eV. The presence of generation–recombination centers, acting like traps, is confirmed by I g – V gs . The localization and the identification of these defects are presented. Finally, the correlation between the anomalies observed on output characteristics and defects is discussed.

Specific on-resistance Ron estimated from current density-voltage characteristics of Schottky diodes on thick layers exhibits variations from tens of mW.cm2 to tens of W.cm2 for different doping levels. In order to understand the occurrence of high on-state resistance, Schottky barrier heights were first estimated for both forward and reverse bias with the application of thermionic emission theory and were in agreement with a literature reported values. Decrease in mobility with the temperature was observed and its dependencies of T–1.3 and T–2.0 for moderately doped and low doped samples respectively were estimated. From deep level measurements by Minority Carrier Transient Spectroscopy, an influence of shallow boron related levels and D-center on dependence of on-state resistance was observed, being more pronounced in low doped samples. Similar tendency was observed in depth profiling of Ron. This suggests a major role of boron in a compensation mechanism thus resulting in high Ron.

Conductance DLTS measurements have been performed on 4H-SiC MESFETs. A broad band due to electron emission by different levels is observed. An additional “hole-like” level with activation energy of 0.9 eV is obtained in linear regime but not in saturation regime. From the results, it is proposed that this “hole-like” signal is due to capture of electron present at a conductive SiC/SiO2 interfacial layer.

Point defects in n-indium phosphide were studied by deep-level transient spectroscopy (DLTS). A radiation-induced bistable defect is found to form under irradiation of a space-charge region of n-InP Shottky-barrier diodes. The transformations of the defect configuration stimulated by heating, illumination, and current flow are studied.

Capture centers (traps) are studied in silicon-on-insulator (SOI) structures obtained by bonding and hydrogen-induced stratification. These centers are located at the Si/SiO2 interface and in the bulk of the split-off Si layer. The parameters of the centers were determined using charge deep-level transient spectroscopy (Q-DLTS) with scanning over the rate window at fixed temperatures. Such a method allows one to study the traps near the Si midgap at temperatures near 295 K. It is shown that the density of traps with a continuous energy spectrum, which are located at the bonded Si/SiO2 interface, decreases by more than four orders of magnitude at the mid-gap compared with the peak density observed at the activation energy E a ≈0.2–0.3 eV. The capture centers are also found in the split-off Si layer of the fabricated SOI structures. Their activation energy at room temperature is E a =0.53 eV, the capture cross section is 10−19 cm2, and the concentration is (0.7–1.7)×1013 cm−3. It is assumed that these capture centers are related to deep bulk levels induced by electrically active impurities (defects) in the split-off Si layer close to the Si/SiO2 interface.

Capacitance–voltage measurements at 77 and 300 K have shown that 11 keV hydrogen ion implantation of n-Si/SiO 2 structure generates defects in the SiO 2 film and at the Si/SiO 2 interface. Deep-Level Transient Spectroscopy spectra reveal the creation of deep levels in the Si substrate. In the accumulation mode tunnelling type conduction through the 120 nm thick SiO 2 film is observed.

We have investigated the electrical property of InGaN quantum dots (QDs) embedded in GaN layer using capacitance-voltage and deep-level transient spectroscopy (DLTS) measurements. The apparent activation energy was observed 0.43 eV below the conduction band edge of barrier layers in InGaN/GaN QDs system. The capture barrier height of InGaN QDs was measured more than about 0.17 eV, showing the existence of strain between QDs and barrier layers. Thus, the bound state of QDs was estimated as 0.26 eV apart from the conduction band edge of the GaN.

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 x 10 7 Ω cm) of the latter wins 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.

The investigation of high-resistivity CdS single crystals by photoelectric deep-level transient spectroscopy (PEDLTS) is discussed. Computer simulation of the experiment is carried out. This simulation enables us to compare the results obtained by the PEDLTS and thermally stimulated conductivity methods. The experimental potentials of these methods are compared.

Biological photoreceptors are very suitable for studies of the structure-function relationship in proteins. Of the many possible candidates, from at least six different families, we discuss here photoactive yellow protein (PYP, a member of the Xanthopsin family). The excellent physical and photochemical stability of PYP has allowed recording of a large amount of data relevant for this characteristic. The timescäles relevant for functional transitions in PYP are most easily studied with transient spectroscopy. Application of the combination of UV/Vis and FTIR spectroscopy has revealed (besides multiple electronically-excited states) the subsequent involvement of the following transient intermediates: I0, pR1, pR 2, pB′, pB and pBdeprot. The structures of these transient intermediates have been characterized with general structural techniques like X-ray diffraction and NMR spectroscopy. Most extensive results have been obtained with X-ray diffraction, applied both in a time-resolved mode and by making use of low-temperature trapping. This has led to a detailed description of the reversible spatial changes in PYP that follow light activation. The structure of the transient intermediates, however, is exquisitely sensitive to constraints from the molecular environment of the protein, like the absence/presence of a crystalline lattice. Extrapolating these results to the signalling state of PYP in vivo is extremely complicated but also very challenging. Rather than measure, one can also simulate and/or calculate the spatial structures of transient intermediates of PYP. This challenge is most straightforwardly tackled with a detailed analysis of the intrinsic dynamics of the stable receptor state of PYP. Such studies have revealed striking similarities in the dynamics of all PAS domain proteins of which a spatial structure has been determined. The next challenge is to properly describe the change in configuration of the chromophore, induced by light, and to expand such simulations to the timescale relevant for completion of this photocycle.

Deep-level transient spectroscopy (DLTS) on HVPE grown n-GaN revealed three dominant traps below the conduction band, commonly associated with HVPE-grown material. In this study, it was found that the concentration of the EC−0.61 eV level is dependent on the biasing conditions: zero bias annealing at 370 K decreases the concentration of the 0.61 eV level to a non-zero value, while reverse bias annealing increases the concentration within the region probed. The change in the defect concentration becomes lower for thicker GaN layers with a lower density of threading dislocations. We tentatively ascribe this behaviour to the neutralisation of the 0.61 eV level by a mobile defect species, which is associated with dislocations present in the material.

The effect of implantation angle on the profile of the vacancy-phosphorus and divacancy centres (VP/V 2 − ) in n-type 0.7–1.1 Ω cm Cz-grown (1 0 0) Si has been examined using depth profiling with deep-level transient spectroscopy. Samples were mounted with 10° twists from the [1 1 0] direction and various tilts from the [1 0 0] direction then implanted with 600 keV P to a dose of 5×10 8 cm −2 . The peak depth of the VP/V 2 − profile exhibits a systematic variation with the implantation angle: narrowing and increasing in peak concentration as the implantation angle is progressively varied from the aligned direction. The defect profiles are approximately 0.3 μm deeper than the peak in the vacancy profile predicted using the binary collision code Crystal-TRIM. Surface-enhanced annihilation of migrating defects has been considered as the cause of this.

The electrical and optical properties of defects introduced into silicon either by plastic deformation at 630°C or by MeV self-implantation and subsequent annealing at 630°C are compared. It is shown, based on the new experimental results and literature data that most of the deep-level transient spectroscopy (DLTS) lines revealed in the deformed crystals coincide with the DLTS signatures of small interstitial clusters in the dislocation-free implanted/annealed samples. In opposite, the photoluminescence (PL) D1–D4 dislocation bands are observed only in the dislocated crystals.

Starting from the data of deep-level transient spectroscopy, the charge fluctuations at the interface between the top Si layer and buried insulator in Si-on-insulator structures are evaluated. The interface was prepared by bonding Si with the thermally oxidized substrate. The magnitude of fluctuations at the interface is found to be equal or exceed (1.5–2.0)×1011 cm−2 against the charge background of ∼5×1011 cm−2 at this interface. It is shown that the fluctuations are most likely associated with the negative charge at the surface states rather than with the fluctuations of the fixed positive charge within oxide.

Defect reactions associated with the elimination of divacancies (V-2) have been studied in n-type Czochralski (Cz) grown and float-zone (FZ) grown Si crystals by means of conventional deep-level transient spectroscopy and high-resolution Laplace deep-level transient spectroscopy (LDLTS). Divacancies were introduced into the crystals by irradiation with 4 MeV electrons. Temperature ranges of the divacancy disappearance were found to be 225-275 degreesC in Cz Si crystals and 300-350 degreesC in FZ Si crystals upon 30 min isochronal annealing. Simultaneously with the V-2 disappearance in Cz Si crystals a correlated appearance of two electron traps with activation energies for electron emission 0.23 eV {E(0.23)} and 0.47 eV {E(0.47)} was observed. It is argued that the main mechanism of the V-2 disappearance in Cz Si crystals is related to the interaction of mobile divacancies with interstitial oxygen atoms. This interaction results in the formation Of V2O centres, which are responsible for the E(0.23) and E(0.47) traps. Electronic properties of the V2O complex were found to be very similar to those of V-2 but energy levels of the two defects could easily be separated using LDLTS. In FZ Si crystals, a few electron traps appeared simultaneously with the V-2 annihilation. The small concentration of these traps compared with the V-2 concentration before annealing prevented their reliable identification. (Less)

Radiation-induced divacancy-related levels in high-purity oxygen-enriched n-type silicon have been studied with the use of deep level transient spectroscopy (DLTS) and Laplace-DLTS. It has been shown that heat treatment at 250°C results in a shift of the divacancy (V 2 )-related peaks observed by 'standard' DLTS. Using Laplace-DLTS it is demonstrated that the shift is due to annealing of V 2 and formation of a new acceptor centre. The new centre has presumably two negative charge states: singly and doubly negative. The formation of the new centre holds a close one-to-one correlation with the annealing of V 2 , indicating that the new centre is a result of divacancy interaction with an impurity or a defect. The close position of the electronic levels of the new centre to that of V 2 suggests a similar electronic and microscopic structure of the new centre to V 2 , and a tentative identification is a divacancy-oxygen centre.

High-resolution photoinduced transient spectroscopy (HRPITS) has been employed to investigate iron-related point defects produced by electron irradiation in high-resistivity silicon. The measurements revealed 16 traps with activation energies ranging from 14 to 530 meV. From the comparison of results, obtained by the HRPITS and ESR measurements performed on the same samples, a trap positioned at Ev+500 meV was attributed to the iron-vacancy pair (Fei)V and that positioned at EV+530 meV to the vacancy complex with two iron atoms (Fei)2V. The former is found to be stable at 400°C, while the latter anneals out at this temperature similarly to the trap at EV+410 meV related to interstitial iron. As a result of the transformation of the (Fei)2V complex and reactions of the interstitial iron with native defects, new iron-related traps with activation energies of 85, 220 and 380 meV are formed.

An optical-capacitance-transient spectroscopy (O-CTS) method was used to characterize defects in epitaxial 6H-SiC. The O-CTS measurements enable us to estimate the optical ionization energy and the optical cross section of these defects. By the deep level transient spectroscopy (DLTS), three peaks were observed, and two of them were identified as E2 and R centers which have been previously reported. We measured the optical cross section for both the centers. By fitting the experimental data with theoretical curves for the optical cross section, we obtained optical ionization energy of 1.58 eV for the R center and 1.0 eV for the E2 center. From the DLTS measurements, the thermal activation energy of the R center is 1.30 eV and that of the E2 center is 0.43 eV. From these results and the previously reported capture energy barrier, the Franck–Condon shift, dFC is estimated to be 0.28 eV for the R center and 0.62 eV for the E2 center.

We investigated the influence of different Cu and Na contents on the electrical properties of Cu(In,Ga)(S,Se) 2 solar cells. The devices were characterized applying admittance spectroscopy and deep-level transient spectroscopy (DLTS). We observed four kinds of deep defect states in differing concentrations in the stoichiometry-varied samples: two acceptor-like deep-level states, one donor-like trap, and a midgap center. In order to characterize the properties of these defect states, we recorded the DLTS capacitance transients of a Na poor sample with different pulse widths (ranging from 100 μs to 1 s duration) at selected fixed temperatures. We discuss the properties of the defect states.

Photo-induced current transient spectroscopy is an efficient technique for the detection and identification of traps in semiconductors. This technique has been used to determine the traps in various semiconductors. CdTe is one of the leading candidates for the development of thin film solar cells; hence, the detection of trap levels in CdTe is of interest for the photovoltaic researchers. In this review special emphasis is given to the photo-induced current transient spectroscopy (PICTS) technique applied in the case of CdTe. The PICTS technique, theory as well as a collection of the majority of the traps in CdTe reported in the literature are presented.

The origin of a broad U band in spectra obtained using deep-level transient spectroscopy (DLTS) of n-GaAs irradiated with fast neutrons and 65-MeV protons was investigated. It is believed that this band is presumably a superposition of two peaks related to two defects P2 and P3 which have been well documented in GaAs and reside within defect clusters. The DLTS spectra were calculated taking into account the nonuniform distribution of these defects in a sample and the built-in electric fields induced by corresponding inhomogeneities.

In this study, we investigate the influence of wet oxidation after nitridation of a gate oxide on the interface states in SiC metal–oxide–semiconductor field-effect transistors (MOSFETs). We used deep-level transient spectroscopy (DLTS) to clarify the mechanism behind the positive shift in the threshold voltage after wet oxidation without any significant decrease in the mobility. We applied DLTS using a small pulse to obtain the depth profile of the states. We found that the density of deep-level states near the interface on the SiC side increased after wet oxidation at 600 and 800 °C, whereas the density of shallow states did not increase. This result indicates that the increase in the deep-level states is related to the threshold-voltage shift, and there is no degradation in the mobility.

Thermal admittance and current deep-level transient spectroscopy techniques have been applied to Schottky diodes fabricated on Mg-doped GaN grown by metalorganic chemical vapour deposition to investigate the dependence of the Mg acceptor levels on the annealing temperature. Both measurements revealed two deep acceptor levels with activation energies of ∼135 and ∼160 meV above the valence band. The former level is only seen when the samples were annealed at temperatures between 650 °C and 700 °C, and its presence corresponds with a significant increase in effective acceptor concentration, as confirmed by capacitance–voltage measurements. Therefore, this acceptor level is considered to dominate the electrical activation of Mg in GaN.

Interface properties of dilute slightly lattice mismatched GaAsN/GaAs (0.35 at.% N) and closely lattice matched InGaAsN (1 at.% In, 0.35 at.% N) heterojunctions (HJs) were studied by means of capacitance–voltage profiling, deep levels transient spectroscopy (DLTS) and current–voltage measurements. It is found that the lattice matched HJs show no electrical breakdown when the space charge region crosses the interface. The carrier concentration profiles in such HJ show, as expected, the accumulation region on the low-bandgap side and the depletion region on the high-bandgap side of the HJ. This is not the case for the GaAsN/GaAs (GaAsN layer on top) and the GaAs/GaAsN (GaAs layer on top) HJ. The density of deep traps in GaAsN, InGaAsN films and in GaAs films grown on GaAsN underlayers was very much higher than in epitaxial GaAs films. The dominant deep centers were the EL6 and the EL3 electron traps. The interface regions of the GaAs/GaAsN and the InGaAsN/GaAs HJs were shown to be enriched by EL3 traps, while for the GaAsN/GaAs HJ those regions were enriched by EL6 traps which was associated with the former films being Ga-rich and thus facilitating incorporation of oxygen on As sites.

A neural network (NN) method has been proposed as a new algorithm for extraction of defect centers parameters in semi-insulating materials from experimental data obtained by photoinduced transient spectroscopy (PITS). The new algorithm is applied to investigate irradiation-induced defect centers in high resistive silicon. The folds on the PITS spectral surface formed due to the presence of defect levels are best fitted with a two-dimensional approximation function with implementation of the NN learning process. As a result, the Arrhenius plots for defect centers are obtained and the parameters of these centers are determined.

This work deals with the performances of two electrical techniques to characterize deep levels in HEMTs. Capacitance Deep Level Transient Spectroscopy (DLTS) is a well-known method and its efficiency is now proved, whereas Drain Current Transient Spectroscopy (DCTS) provides information about the location of traps in the structure. Experimental results establish the complementarity of these two techniques.

High-temperature isothermal capacitance transient spectroscopy (H-ICTS) measurements were conducted to characterize near mid-gap defects, which are the origin of the memory effect in Ni/p-GaN Schottky contacts. A large single peak was detected only under the forward bias conditions. This indicates that the defects were located in the vicinity of the interface. The change of the peak height and position of the ICTS curves under various bias conditions were qualitatively interpreted by the distribution of the defects and the current flow effect.

Detector-grade undoped chemical vapor deposited (CVD) diamond samples have been studied with thermally stimulated currents (TSC) and photoinduced current transient spectroscopy (PICTS) analyses in the temperature range 300–650 K. Two previously unknown defects have been identified, characterized by activation energies E1=1.14 eV and E2=1.23 eV, cross sections of about σ≈10−13 cm2 and concentrations of Nt≈1016 cm−3. They have been clearly observed by PICTS and isolated in TSC measurements by use of a fractional annealing cycle in the temperature range 300–400 K. Due to their trap parameters, in particular the high cross section, the levels corresponding to E1 and E2 are characterized by capture times of the order of 10–100 ps. A dominant TSC peak observed at ≈500 K has been also investigated and has been resolved into four components with activation energies of the order of 1 eV and cross sections in the range 10−19–10−17 cm2. Three of these levels exhibit a fast capture rate (0.1–10 ns) in spite of their ...

High-resolution photoinduced transient spectroscopy (HRPITS) has been applied to study the electronic properties of grown-in point defects in semi-insulating (SI) GaAs bulk crystals grown by liquid encapsulated Czochralski (LEC) and vertical gradient freeze (VGF) methods. The novel method, which represents the significant improvement of the earlier PITS technique, relies on the extraction of trap parameters from the digitally recorded photocurrent transients by means of the correlation procedure. The influence of the crystallisation conditions on the defect structure of high resistivity GaAs is compared. In the VGF material the concentrations of traps P6 (0.05 eV), P7 (0.08 eV), P12 (0.18 eV), EL14 (0.22 eV) and EL3 (0.58 eV), tentatively identified as V As −/0 , Ga As 0/− , B As −/−− , V Ga –V As and O i –V As , respectively, are found to be much lower than in the LEC material.

Defects in high quality 4H silicon carbide epilayers have been studied using Deep Level Transient Spectroscopy (DLTS) and Minority Carrier Transient Spectroscopy (MCTS). Both intrinsic defect related centers HS1, Z(1/2). EH6/EH7 and shallow and deep boron centers were found. Electrical properties of the boron related traps are analyzed. Comparison with the optical decay measurements shows that boron is related to the observed lateral variations of the minority carrier lifetime in low doped 4H-SiC epilayers.

Further evidence was found that the 0.8 eV luminescence band in GaAs is correlated to the EL6 defect as identified by photo induced current transient spectroscopy (PICTS). From luminescence topography arguments are put forward that the EL6 defect should not be the dominant recombination centre in GaAs. By the application of microwave detected PICTS it could be shown that the EL6 is definitely not a relevant recombination centre. Recombination takes place most probably via different, partially not jet identified centres.

Non-destructive and spatially resolved (35 μm) characterisation methods for high resistivity GaAs and epitaxial substrates are presented. Microwave detected photo induced current transient spectroscopy (PICTS) is a further development of the already existing method Microwave detected photoconductivity (MDP). Using various GaAs samples of different preparations, the possibilities of these new tools are demonstrated along with the first results for technologically relevant extrinsic and intrinsic defects.

The rapid degradation of Se-doped GaAs0.6P0.4 light-emitting diodes is of prime importance in reliability studies of optical devices using III–V compound semiconductors. Marked changes are observed at the junction of Se-doped GaAs0.6P0.4 light-emitting diodes, because they degrade rapidly, in contrast to Te-doped GaAs0.6P0.4 light-emitting diodes, which degrade gradually. Here, this rapid degradation is investigated using aging tests under various conditions by a capacitance–voltage method and deep-level transient spectroscopy. We discuss the differences in the degradation mechanisms for the two diodes and propose a model for the rapid degradation.

Conducting and semi-insulating crystals of GaAs grown by vertical Bridgeman (VB) and liquid encapsulated Czochralski (LEC) methods were studied by means of deep levels transient spectroscopy, photoinduced current transient spectroscopy, panchromatic microcathodoluminescence, optical absorption and electrical measurements. The most prominent traps observed in both types of crystals were the EL8, EL6, EL5, EL3 and EL2 electron traps. The results suggest that VB crystals are similar to LEC GaAs crystals grown from slightly Ga rich melts. The electrical properties and uniformity of VB crystals were greatly improved by the standard 950 °C annealing procedure.

In this paper, the properties of point defects in Cd1−xZnxTe1−ySey (CZTS) radiation detectors are characterized using deep-level transient spectroscopy and compared between materials grown using two different methods, the Bridgman method and the traveling heater method. The nature of the traps was analyzed in terms of their capture cross-sections and trap concentrations, as well as their effects on the measured charge-carrier trapping and de-trapping times, and then compared for the two growth techniques. The results revealed that Se addition to CdZnTe can reduce the VCd− concentration. In Travelling Heater Method (THM) and Bridgman Method (BM) grown CZTS detectors, besides a few similarities in the shallow and medium energy traps, there were major differences in the deep traps. It was observed that the excess-Te and lower growth-temperature conditions in THM-grown CZTS led to a complete compensation of VCd− and two additional traps (attributed to Tei− and TeCd++ appearing at around Ev + 0.26 eV and Ec − ...

Close-spaced vapor transport (CSVT) provides a plausible path to lower the costs of GaAs deposition as it uses only solid precursors and provides precursor utilization in principle approaching 100%. However, the use of H2O as a transport agent causes O to be incorporated in CSVT films, and O has been associated with a number of electrically active defect centers in GaAs, which decrease minority carrier lifetimes. Using deep-level transient spectroscopy, we study the effect of H2O concentration and substrate temperature on electron trap concentrations in n-type GaAs. We find that the most-prominent O-related center (ELO) typically has a much higher concentration than the center usually associated with As antisites (EL2), but that overall defect concentrations can be as low as those in films deposited by common vapor phase techniques. The trends with increasing H2O concentration suggest that ELO is most likely a defect complex with two As antisites. We also consider the optimal conditions for achieving high...

Experiments on proton irradiation with energy of 150 KeV, 8 MeV and 1 GeV were made. Capacitance–voltage characteristics measured at 650 K showed that 8 MeV and 1 GeV proton irradiation of 6H-SiC leads to an increase of uncompensated donor concentration. However, donor concentration in 6H-SiC remains unaffected after 150 keV proton irradiation. Deep centers were investigated by deep levels transient spectroscopy (DLTS). Results of C–V measurements are interpreted using DLTS data. The results obtained show the possibility of uzing proton irradiation for producing local high-resistance regions in SiC devices not intended for high-temperature applications.

High resolution Laplace minority carrier transient spectroscopy (LMCTS) has been used to study defects in gas source molecular beam epitaxy grown Si/Si0.855Ge0.145 strained quantum wells. In LMCTS, the minority carrier emission transient is analysed and detailed emission properties of minority carrier traps which have similar energy can be characterised. The technique was evaluated by comparing LMCTS of a Au : H hole trap, G3, in n-type silicon with Laplace deep level transient spectroscopy of the same trap in p-type silicon. Both techniques confirm that this level consists of two states, as previously suggested in the literature. MCTS was then applied to the n-type Si/SiGe quantum well sample, and five-hole traps were observed. A level at 95 K in the MCTS spectrum was identified as a possible candidate for hole emission from the quantum wells. LMCTS showed that the emission rate of this hole trap exhibited only a slight temperature dependence compared to that exhibited by hole states associated with isolated point defects. This is attributed to holes tunnelling out of the quantum well assisted by the electric field present in the experiment.

Dislocated Si, SiGe, SiC, and SiGeC n-type heterostructures, grown by molecular beam epitaxy, were characterized by capacitance–voltage profiling and deep-level transient spectroscopy. Exclusively dislocation-related defects were found in the different layers, which correspond to the well-known defects found in plastically deformed silicon.

The pseudomorphic AlGaAs/InGaAs/GaAs MODFET, intended for future applications in cryoelectronics, has been investigated. In the temperature range of 10–350 K no collapse nor Kink effect have been detected. However, a threshold shift has been observed which is thought to be associated with electrically active defects in the heterostructure. The related deep levels are directly characterized by two electrical techniques: capacitance deep level transient spectroscopy and drain current transient spectroscopy. Experimental results establish the complementarity of both techniques.

Using electrical techniques (deep-level transient spectroscopy, capacitance and current-voltage measurements) applied to different types of p/n junctions, we correlate the concentration of the EL2 defect with properties directly related to the rate of recombination of minority carriers in a Czochralski-grown material and in epitaxial layers. The results demonstrate that this defect is responsible for minority carrier lifetime in both materials.

Capacitance–voltage measurements and deep-level transient spectroscopy have shown that RF hydrogen plasma treatment of thin (13 nm) SiO 2 /p-Si structures at 20, 100 and 300°C generates defects in the oxide, at the SiO 2 /Si interface and in the near-surface region of Si substrate. The density of these defects depends on the substrate temperature during plasma exposure. The concentration of plasma-induced defects is the highest at 20°C. With increasing treatment temperature the densities of positive oxide charges, donor-like interface traps and deep levels in the Si bulk decrease.