Masamori Iida

Fabrication of a diamond field emitter array

A diamond field emitter array has been fabricated. by Chemical vapor deposition. Diamond was grown on an inverted pyramidal‐shape Si substrate followed by removal of the substrate. The fabricated array was placed in a high vacuum pumping system with the pressure of ∼10−7 Torr and the emission current as a function of the anode voltage was measured. The distance between the tungsten anode and the diamond surface was held constant at 100 μm throughout the measurement. As a result, a current larger than 10−4 A was obtained for an anode voltage of 6 kV. A linear relationship in the Fowler–Nordheim plot indicated the existence of electron field emission from the fabricated diamond field emitter array.

Synthesis of n-type semiconducting diamond film using diphosphorus pentaoxide as the doping source

An n-type semiconducting diamond film has been synthesized by the hot filament CVD method using diphosphorus pentaoxide as the doping source. The obtained film was identified as polycrystalline diamond containing few sp2 components by means of several methods including Raman spectroscopy. From measurements of the Hall effect and the Seebeck effect, the film was found to be an n-type semiconductor.

Electrical properties of Schottky barrier formed on as‐grown and oxidized surface of homoepitaxially grown diamond (001) film

Characteristics of Schottky barriers formed on homoepitaxial diamond film have been studied. Current–voltage characteristics of Al contacts on both the as‐grown film and the oxidized film show rectification. On the other hand, ohmic property is observed on Au/as‐grown film while Au/oxidized film shows rectification. These results imply that the mechanism of the barrier formation on the as‐grown diamond is drastically changed by oxidation. The difference of electrical properties between the as‐grown film and the oxidized film is also observed from capacitance–voltage characteristics. This result suggests that additional acceptors which are not related to boron, exist in the as‐grown film and disappear after oxidation.

Synthesis of B-doped diamond film

Abstract Boron-doped diamond films have been synthesized by the thermal filament CVD method. As the doping source, boron trioxide powder was used instead of diborane. The films obtained were identified as diamond by several methods including Raman spectroscopy. The resistivity of the films was inversely proportional to the doping concentration over four order. p-Type electrical conduction was also confirmed by measuring the Seebeck effect.

p‐n junction diode made of semiconducting diamond films

A diamond p‐n junction diode fabricated by the chemical vapor deposition technique, shows distinct rectification characteristics. From the electron beam induced current measurement, the existence of a depletion region or a space‐charge region around the interface between the n‐ and p‐type semiconducting diamond layers was identified.

Fabrication of a diamond p-n junction diode using the chemical vapour deposition technique☆

Abstract A diamond p − n junction diode has been fabricated by the chemical vapour deposition technique. Diphosphorus pentaoxide and boron trioxide were used for the doping sources for the n - and p -type layers, respectively. The diode shows distinct rectification characteristics at 300 K room temperature. This diode shows rectification even at 370 K and this result implies the possible use of diamond as a semiconductor in high temperature conditions.

Doping of diamond

Abstract Semiconducting diamond films were deposited by the conventional hot filament chemical vapour deposition technique. Boron trioxide and diphosphorus pentaoxide have been used as the dopants for p- and n-type films respectively. The films obtained were identified as diamond by means of scanning electron microscopy, electron diffraction and Raman spectroscopy. The impurity concentrations in the films were evaluated using secondary ion mass spectroscopy. The semiconducting properties of the films were confirmed by measuring the resistivity, the Hall effect and the activation energy of the conductivity.

Electrical and optical properties of chalcogenide amorphous semiconductors modified with Ni

Abstract The electrical and optical properties of the chalcogenide semiconductor (Se 32 Te 32 As 4 Ge 32 ) 100− x Ni xitx have been studied. As the Ni concentration is increased the electrical dc conductivity is drastically increased and variable range hopping conduction becomes dominant even above room temperature. The optical energy gap decreases with the Ni concentration from 1.18–0.95 eV. Ni-atoms in the chalcogenide semiconductor donate free electrons which occupy the gap state. This occupation causes the shift of the Fermi level toward the conduction band. It is an effect of this shift that the thermal activation energy is decreased. The decrease in optical energy gap is independent of the shift of the Fermi level and is ascribable to the appearance of the additional level located at 0.95 eV above the top of the valence band. This level originates from the 3d-level of the Ni-atom.

Characterization of semiconducting diamond film and its application to electronic devices

Abstract A diamond p-n junction diode has been fabricated by the chemical vapour deposition technique. Diphosphorus pentaoxide and boron trioxide were used for the doping sources for the n- and p-type diamond films respectively. The films were identified as diamond from the results of the electron diffraction and Raman spectroscopy. The diode exhibited distinct rectification characteristics. The formation of the depletion layer was confirmed from the result of the electron-beam-induced current measurement.

Isothermal capacitance transient spectroscopy measurements on polycrystalline diamond/hydrogenated amorphous silicon heterojunctions

A deep level in boron‐doped polycrystalline diamond films located approximately 0.6 eV above the valence‐band edge has been found using isothermal capacitance transient spectroscopy (ICTS) measurements. p‐n heterojunctions between polycrystalline diamond and hydrogenated amorphous silicon were used in the study. The density and the hole‐capture cross section of the deep level traps were determined from the temperature dependence of ICTS spectra and found to be 2×1016 cm−3 and 1×10−17 cm2, respectively.