Eizaburo Yamada

Low‐frequency 1/f noise in MOSFET’s at low current levels

Low‐frequency 1/f noise in Si n‐channel MOSFET’s is measured at 300 and 77 K. It is found that the equivalent input‐noise resistance Rng increases at low current levels from 100 to 10−2 μA in both the saturation and linear regions. A theory is developed to account for this characteristic, assuming the activated conduction at low electron concentrations due to the surface potential roughness as proposed by Chen and Muller. Theoretical calculations are made for the linear region of operation. Excellent agreement is obtained between the theory and the experiment at both temperatures.

Doping Effect in Chalcogenide Glasses

Electronic properties of doped chalcogenide glasses are discussed on the basis of the Street-Mott model by taking a finite width of gap states into account. The conduction activation energy depends strongly on the shape of the gap state energy distribution. A rather gradual change in the activation energy with the increas of impurity concentrations, often observed in experiments, is well reproduced by introducing relatively small values for the distribution width. It is then possible to estimate the fraction of dopant atoms, which actually change conductivity, by comparing the results of the present model with experiments.

Theory of hot electron magnetophonon resonance in longitudinal magnetic fields

Abstract Longitudinal magnetoresistance of hot electrons in n—InSb at low temperatures is calculated taking into account the quantization of the conduction band into Landau subbands. Negative magnetoresistance and magnetophonon resonance minima are obtained as combined effects of inter-subband transition and optical phonon emission.

Theory of trap controlled transient photoconduction in chalcogenide glasses

Abstract The motions of charges moving through chalcogenide glasses is discussed in terms of multiple trapping extended state transport, considering negative U centers as significant traps. Due to the amphoteric nature of these centers, a slight difference in excitation energies of electrons and holes from D° results in a qualitative differences in transport of both charges. When impurity atoms are added, a region where charges show diffusive transport appears.