J Woods

Bio: J Woods is an academic researcher. The author has contributed to research in topics: Space charge. The author has an hindex of 1, co-authored 1 publications receiving 11 citations.

Space-charge-limited currents and electron traps in cds crystals

Abstract: Thermally stimulated currents have been measured after the electrical injection of electrons in thin insulating crystals of cadmium sulphide which can support large space-charge-limited currents. Two trapping levels which lie 0.41 ev and 0.61 ev below the conduction band are filled with electrons when currents in the vicinity of the traps-filled limit are passed. When currents which lie within the region of Child's Law for solids are allowed to flow the concentration of trapping levels at 0.61 ev decreases while the number of levels at 0.41 ev increases. Measurements of the dark current in the ohmic region suggest that the 0.41 ev trapping complex is stable at temperatures below 0°C and is converted to a complex with a level at 0.61 ev at higher temperatures.

Electric Field Effects in Trapping Processes

Abstract: The effects of moderate electric fields (≤3×103 V/cm) on the trapping processes in photosensitive CdS‐CdSe single crystals have been investigated using photoelectronic techniques Possible mechanisms such as injection of electrons, extraction of holes, dielectric polarization due to inhomogeneities, Joule heating, electrochemical effects, impact ionization, field‐assisted tunneling, and field‐associated changes in the capture cross sections and/or thermal emission probabilities of traps are considered Evidence is presented for the reality of field‐associated changes in trapping parameters in the absence of all the other possible effects Results are consistent with a field emptying of Coulomb‐attractive traps by a decrease in the trap depth and a decrease in the capture cross section of traps The conclusions may be relevant to the interpretation of space‐charge‐limited current data and to mechanisms capable of leading to improved photoconductor speed for low intensity excitation

Electron trapping levels in cadmium selenide single crystals

Abstract: Measurements of space‐charge‐limited currents have been performed on CdSe single crystals between 77 and 400 °K. Four groups of electron trapping levels have been found at 0.64, 0.49, 0.35, and 0.167 eV, with densities ranging from 5 × 1010 to 1013 cm−3. A check of the results with photocurrent vs light intensity and thermally stimulated currents measurements is presented. The origin and the nature of these centers is discussed and correlated with mobility values measured in the crystals investigated. Finally, contacts and geometry considerations are reported.

Thermally stimulated current analysis

Abstract: Difficulties experienced in obtaining reproducible results from thermally stimulated current analysis have led to a reconsideration of the basic mechanisms involved, and it is shown that the thermally stimulated current spectrum is critically dependent on the optical stimulation and thermal emptying procedures. It may not always be necessary to explain the appearance and disappearance of traps by other more complicated models, for example photosynthesis. A brief survey is made of other factors giving deviations from the basic mechanism.