We have investigated by deep level transient spectroscopy the hole and electron trap defects introduced in n-type Ge during electron beam deposition (EBD) of Pd Schottky contacts. We have also compared the properties of these defects with those introduced in the same material during high-energy electron irradiation. Our results show that EBD introduces several electron and hole traps at and near the surface of Ge. The main defect introduced during EBD has electronic properties similar to those of the V–Sb complex, or E center, introduced during high-energy particle irradiation of Ge. This defect has two levels E0.38 and H0.30 that correspond to its (−−,−) and (−,0) charge states.

We have developed a compact streak camera suitable for measuring the duration of highly charged subrelativistic femtosecond electron bunches with an energy bandwidth in the order of 0.1%, as frequently used in ultrafast electron diffraction ͑UED͒ experiments for the investigation of ultrafast structural dynamics. The device operates in accumulation mode with 50 fs shot-to-shot timing jitter, and at a 30 keV electron energy, the full width at half maximum temporal resolution is 150 fs. Measured durations of pulses from our UED gun agree well with the predictions from the detailed charged particle trajectory simulations.

The influence of high energy electron (HEE) irradiation from a Sr-90 radio-nuclide on n-type Ni/4H-SiC samples of doping density 7.1 × 10 15 cm -3 has been investigated over the temperature range 40-300 K. Currentvoltage (I-V), capacitance-voltage (C-V) and deep level transient spectroscopy (DLTS) were used to characterize the devices before and after irradiation at a fluence of 6 × 10 14 electrons-cm -2 . For both devices, the I-V characteristics were well described by thermionic emission (TE) in the temperature range 120 -300 K, but deviated from TE theory at temperature below 120 K. The current flowing through the interface at a bias of 2.0 V from pure thermionic emission to thermionic field emission within the depletion region with the free carrier concentrations of the devices decreased from 7.8 × 10 15 to 6.8 × 10 15 cm -3 after HEE irradiation. The modified Richardson constants were determined from the Gaussian distribution of the barrier height across the contact and found to be 133 and 163 Acm −2 K −2 for as-deposited and irradiated diodes, respectively. Three new defects with energies 0.22, 0.40 and 0.71 eV appeared after HEE irradiation. Richardson constants were significantly less than the theoretical value which was ascribed to a small active device area.

Ions arriving at a semiconductor surface with very low energy (2 -8 eV) are interacting with defects deep inside the semiconductor. Several different defects were removed or modified in Sb-doped germanium, of which the E-center has the highest concentration. The low fluence and low energy of the plasma ions implies that the energy has to be able to travel in a localized way to be able to interact with defects up to a few microns below the semiconductor surface. After eliminating other possibilities (electric field, light, heat) we now conclude that moving intrinsic localized modes (ILMs), as a mechanism of longdistance energy transport, are the most likely cause. This would be striking evidence of the importance of ILMs in crystals and opens the way to further experiments to probe ILM properties both in semiconductors and in the metals used for contacts. Although most of the measurements have been performed on germanium, similar effects have been found in silicon.

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We have systematically investigated the effects of high-temperature annealing on ZnO and ZnO devices using current voltage, deep level transient spectroscopy (DLTS) and Laplace DLTS measurements. Current-voltage measurements reveal the decrease in the quality of devices fabricated on the annealed samples, with the high-temperature annealed samples yielding devices with low barrier heights and high reverse currents. DLTS results indicate the presence of three prominent defects in the as-received samples.

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Current-voltage, capacitance-voltage and conventional deep level transient spectroscopy at temperature ranges from 40-300 K have been employed to study the influence of alpha-particle irradiation from an 241 Am source on Ni/4H-SiC Schottky contacts. The nickel Schottky barrier diodes were resistively evaporated on n-type 4H-SiC samples of doping density of 7.1 × 10 15 cm −3 . It was observed that radiation damage caused an increase in ideality factors of the samples from 1.04 to 1.07, an increase in Schottky barrier height from 1.25 to 1.31 eV, an increase in series resistance from 48 to 270 Ω but a decrease in saturation current density from 55 to 9 × 10 −12 Am −2 from I-V plots at 300 K. The free carrier concentration of the sample decreased slightly after irradiation. Conventional DLTS showed peaks due to four deep levels for as-grown and five deep levels after irradiation. The Richardson constant, as determined from a modified Richardson plot assuming a Gaussian distribution of barrier heights for the as-grown and irradiated samples were 133 and 151 Acm −2 K −2 , respectively. These values are similar to literature values.