The short coming of the conventional film-screen systems arises from limited dynamic range due to the film latitude and Swank noise from the screen and film granularity that limits the system rather than quantum fluctuations. A thin intensifying screen is used to achieve better spatial resolution; however thin screens also have limited detector quantum efficiency. Most currently available digital X-ray systems use scanned-slit geometries to minimize tehe required detector area and minimize system complexity. Scanned-slit systems achieve also efficient rejection of Compton scattered X-rays by suffering significant X-ray tube loading in comparison to conventional large-field imaging geometries. There remains a significant clinical need in production of detection systems with sufficiently high spatial resolution and detection quantum efficiency. An improvement of digital radiography compared to conventional systems is the high dynamic range. Futhermore real-time data acquisition is possible and digital image processing can be performed. A digital image representation has become feasible because of the availability of digital mass storage media.

The Hall-effect and conductivity of diamond polycrystalline films doped by boron impurity (N-alpha congruent to 10(19) cm(-3)) were measured over a temperature range of 300 divided by 650 K. A temperature transition from the hopping epsilon(3) - conductivity to the hole transport through Impurity band formed by exited states of the accepters was observed. Analyzing the Hall- effect data by the model of mixed conductivity, the hole mobility (mu Eta congruent to 10 cm(2)/ V.s) in the band and energy gap between this band edge and the boron ground state level (congruent to 220 meV) were estimated.

Li salts (LiCiO4 and Li2CO3) were used for diffusion under bias in polycrystalline diamond films. Hot-probe and conductance measurements were performed. A change in conductance of more than 10 orders of magnitude due to diffusion was observed. The p-type conductivity was obtained by conventional hot-probe measurements. The sign of the thermoelectric power was found to depend on the electric field normal to the surface. A hypothesis was advanced regarding the existence of a p-type inversion layer on the surface of the n-type bulk diffused layer.

The electrical characteristics of thick diamond polycrystalline films grown on metal substrates by the method of chemical crystallization from the electrically activated gas phase were investigated. The active and reactive components of the complex conductivity of the films were measured as functions of the frequency and temperature in the ranges 10-10(5) Hz and 80-900 K respectively. For the first time, charge-based deep-level transient spectra of insulating diamond films were also obtained using rate window scanning.From the analysis of the experimental results, three carrier transport mechanisms were concluded to be possible, each of them being dominant in different temperature ranges: the grain-boundary-barrier-limited currents at high temperatures, the conductivity along the disordered intercrystallite boundaries through the allowed band tails at intermediate temperatures, and jumping conductivity between localized states of the intercrystallite boundaries near the Fermi level at low temperatures. The parameters of trapping centres were determined. The dependences of the integral density of the recharging trap centres, and the frequency an temperature dispersions of the electrical characteristics were determined as functions of the CH4 concentration in the gas mixture during the diamond film crystallization.

Deep-level transient charge spectroscopy (QDLTS) measurement is described. The technique is used to investigate energy levels of tin in AlxG1−xAs. The QLDTS spectra have multiple peaks which show the multilevel nature of the tin donors.

Electrical and photoelectrical characteristics of heterostructures fabricated by ion-plasma deposition of thin amorphous carbon films onto silicon substrates were studied. In particular, current-voltage, capacitance-voltage and charge transient characteristics were measured at different illumination intensities. A charge memory effect, resulting in a frequency dispersion of electrical and photoelectrical characteristics was observed, and its dependence on the structural parameters of the films were investigated. Multilayer structures were prepared using thin (less than or equal to 5 nm) amorphous hydrogenated carbon layers with two values of forbidden gap (mobility gap). the narrow gap layers being wells and the wider gap layers being barriers. Current-voltage and capacitance-voltage characteristics of these structures revealed some features which are related to the confinement of carriers in the potential wells and their resonant tunneling through barriers. Possible applications of the structures as photosensors and dynamical memory elements were demonstrated.

Multilayered quantum-dimensional structures were investigated containing 1 to 10 potential wells produced by alternating diamond-like carbon films with two values of the forbidden gap width (mobility gap) on silicon substrates. Current-voltage, charge-voltage and charge transient characteristics for different temperatures and illumination intensities as well as photoresponse kinetics were studied. Areas of a negative differential conductance were revealed at both low and room temperatures, which may be considered as a manifestation of a resonant tunnelling injection of minority carriers with the pulse normal to the quantum-dimensional layers of the diamond-like carbon films. This phenomenon becomes significantly more pronounced when the multiple quantum well (MQW) structures are illuminated, being strongest in the samples having the thickness of the two outer barrier carbon films of the MQW structure two times lower than that of the internal barrier films. The investigation results confirm a possibility of manufacturing and using MQW structures based on diamond-like carbon films in micro- and nanoelectronics, particularly as resonant tunnelling devices (diodes, transistors, etc.).

Measurements were made of current-voltage, capacity-voltage and charge-transient characteristics including Q-DLTS spectra for structures having thin (10 to 103 Å) films of diamond-like carbon on Si and GaAs substrates. A memory storage effect resulting from the capture of injected charge carriers on localized defect states in thin diamond-like carbon films has been observed. Dependence of information charge storage time on temperature, intensity and energy of the illumination as well as the captured charge magnitude on the amplitude and duration of the injecting voltage pulse were determined. The possibility of using the manufactured structures as reversible dynamic memory devices, nonlinear parametric elements, and sensitive photosensors have been demonstrated.

The complex is designed for study and determination of the parameters of semiconductors and semiconductor structures by means of methods based of analysis of the charge-relaxation characteristics and kinetics of photoresponse. The complex measures: volt-coulomb characteristics in the pulse and voltage-scanning modes with the charging-process duration and recording time of the charge leakage from the specimen independently set within 2.10(-6)-5.10(2) sec; deep-level charge-relaxation spectra with temperature scanning (80-500 K) or time-window scanning (2.10(-6)-2.10(2) sec) with variation of the charge states of the levels in the semiconductor structure by voltage or light pulses; photoresponse kinetics; volt-ampere characteristics under quasistatic and dynamic conditions; and a number of other characteristics.

The photoresponse spectra V(ph)(h-omega) were determined for multi-quantum-well (MQW) p+-i-n+ GaAs-Al0.3Ga0.7As structures in the photon energy range (h-omega) from 1.4 to approximately 2.2 eV at temperatures approximately 300 and approximately 80 K. The voltage responsivity was determined. A study was made of the influence of a constant bias voltage on the spectra of V(ph)(h-omega). Reversal of the exciton peaks in the photoresponse spectra was observed and a model of the physical process responsible for this reversal was proposed. It was found that the dependences V(ph)(h-omega) could be used in studies of the energy spectra of quasitwo-dimensional exciton states, determination of the thicknesses of quantum wells, and detection of planar inhomogeneity of an internal electric field in MQW p+-i-n+ structures. The current-voltage characteristics of illuminated structures had regions of rapid variation of the differential conductance and of a dynamic bistability due to resonant tunnel photoinjection of nonequilibrium carriers, which were observed both at T almost-equal-to 80 K and at room temperature.