Kohzoh Masuda

Effects of ion etching on the properties of GaAs.

Effects of ion etching on the optical properties and lattice disorder of GaAs were studied by means of photoluminescence, He backscattering, and enhanced chemical etching. The photoluminescence intensity excited by a He-Cd laser (3250 A), which penetrates a distance of approximately 150 A into GaAs, is decreased to less than 20% of the initial value after ion etching by 100-eV Ar and recovered almost completely by 450 degrees C annealing. Helium backscattering and electron diffraction pattern indicate the existence of an amorphous layer, the thickness of which is 20% larger than the value estimated by LSS theory. Photoluminescence measurement shows that beyond this amorphous region there are distributed a lot of nonradiative recombination centers as well as radiative recombination centers which diffuse into the bulk. The depth of this distribution is larger than that of the amorphous region by 1 order of magnitude.

Ion Implantation in Semiconductors

Publisher Summary This chapter examines the different aspects of ion implantation in semiconductors. Ion implantation is a superior technique for producing new materials, which are very difficult or impossible to produce by chemical methods. Ion implantation is the introduction of foreign atoms or lattice irregularities in the solid. An important feature of the introduction of foreign atoms by ion implantation is that this method is applicable to all kinds of materials. Depth profiles of the implanted ions can be calculated reasonably well by the Lindhard theory in the case of amorphous material. Apart from the bombardment techniques, which can move the atom during the measurement, possible methods for detecting the existence of impurity atoms and their location consist of nuclear magnetic resonance and electron spin resonance measurements. It is found that multivacancies rather than single vacancies are normally produced by ion implantation because of the high flux density and high total dose of the implanted ions. In the case of single crystals, enhancement of the penetration was observed. The radiation enhanced diffusion is assumed to result from the increase of radiation induced vacancies, the occurrence of the secondary channeling and interstitial migration.

Electroluminescence of anthracene with powdered graphite electrodes and ambient gas effects on the electrodes

Double‐injection electroluminescence of anthracene with a special electrode has been studied. The electrode was efficiently capable of injecting both electrons and holes into anthracene. Both current and electroluminescence intensity were markedly enhanced by a factor of about 30 when the ambient gas of the cathode was changed from air to nitrogen. The emitted light which peaked at 4440 A was generated with an external quantum efficiency ranging from 4 to 6%.

ENHANCED DIFFUSION OF HIGH‐TEMPERATURE ION‐IMPLANTED ANTIMONY INTO SILICON

Concentration profiles of 20‐keV high‐temperature ion‐implanted antimony into a silicon single crystal were measured by means of radioactivation analysis and the enhanced diffusion was observed. The concentration profiles were found to be independent of temperature over the range between 500 °C and 800 °C and to be dependent on the dose rate of ion implantation. The diffusion coefficient of antimony is estimated to be about 1.1×10−15 cm2/sec for the dose rate of about 1.2×1012 ions/cm2 sec and about 6.6×10−15 cm2/sec for that of about 7.2×1012 ions/cm2 sec. The measured concentration profiles are in good agreement with the calculated concentration profile. These results are explained on the basis of a vacancy mechanism.

Effects of ion‐implanted atoms upon conduction electron spin resonance (CESR) in a Si : P system

The behavior of the conduction electron spin resonance of ion‐implanted (Siu2009:u2009P) u2009:u2009Sb and (Siu2009:u2009P) u2009:u2009Te systems is observed to be strongly modified by the presence of Sb or Te substitutional atoms in shallower surface layers; i.e., the ESR signal shows an anomalous line broadening. The origin of the anomalous broadening may be due to the spin‐orbit interaction between the conduction electrons contained within a thin layer (⩽25 μm) and implanted Sb or Te impurities contained within a thin layer (.=.0.1 μm).

ENHANCED DIFFUSION IN ION-IMPLANTED SILICON.

Abstract Concentration profiles of 20 keV ion implanted antimony into silicon single crystals are measured by radio-activation analysis and the enhanced diffusion of antimony is observed. The concentration profiles and the diffusion coefficient of antimony are found to be independent of temperature over the range between 500 and 800°C during ion implantation. The enhancement of diffusion during annealing after room temperature ion implantation is the same as that during high temperature ion implantation. The diffusion coefficient is estimated to be 1.1 × 10−15 cm2/sec for diffusion during high temperature ion implantation and that during annealing after room temperature ion implantation. The measured concentration profiles agree very well with the calculated concentration profiles. These results are explained on the basis of a vacancy mechanism.

Heterostructure CdS1−xSex−CdS surface lasers for integrated optics

Heterostructure CdS1−xSex−CdS surface lasers which have a larger refractive index and a smaller band gap than CdS substrates were fabricated by vapor phase epitaxy and their laser characteristics at 80 K were studied by using a nitrogen gas laser excitation. The Se profiles which were deduced from the fluorescence wavelength were steplike but graded due to diffusion. The optical gain of the epitaxially grown surface layer was larger than that of CdS single crystal owing to optical confinement. By stripe geometry excitation, an intense axial single−mode output was observed up to the excitation intensity three times as high as the threshold 70 kW/cm2. Optical coupling between the active and passive layers was observed in the samples which have a double epitaxial layer.

Electron spin resonance of ion-implanted Si:P systems

Abstract The ESR of Si:P and (Si:P):Sb systems made by ion implantation has been observed. An anomalous line-broadening appears in the (Si:P):Sb system, and is considered to be due to the large spin-orbit interaction of Sb donor impurity. The effective spin-lattice relaxation time, T 1 eff , of both the systems is found to be dominated by a thin layer with the shortest relaxation time T 1 ( χ ).

Concentration Profiles of Arsenic Implanted in Silicon

Concentration profiles of 35 to 130KeV arsenic ions have been measured by means of neutron-activation analysis. The profiles are composed of two parts; one of nearly gaussian shape around the peak concentration region and the other of the nearly exponential shape at the deeper region beyond the peak. The nearly gaussian components agree with the prediction by the LSS theory. The exponential shape was not observed in heavily damaged silicon. The slope of the exponential tail is independent of a dose, substrate temperature and ion energy. It is proposed that this tail is caused by a rapid diffusion process such as interstitial diffusion.

Optical Absorption Measurements of α-Hydronaphthyl Radical Produced in Naphthalene by Electron Beam Irradiation and Hydrogen Atom Bombardment

Abstract The optical absorption was measured of a naphthalene single crystal irradiated with electron beam and of naphthalene powder bombarded with hydrogen atom, both at room temperature. The optical bands at 380 mμ and 540 mμ observed for both samples, were attributed to α-hydronaphthyl radical by the comparison of annealing behaviors of optical absorption bands with that of the ESR signal of this radical.