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The post-cycling data retention of filamentary operated resistive random access memory (ReRAM) can be improved by minimizing conductive filament expansion during pulse cycling. We find that filament size gradually grows with increasing pulse cycles due to oxygen diffusion from the region surrounding each filament. To achieve long term use of ReRAM while suppressing filament expansion, the key is to control both electric power and pulse width input during switching. We minimize CF expansion based on this concept and demonstrate long data retention even after 106 pulse switchings under optimized reset conditions.

We have demonstrated ZnSe-based white light emitting diodes (LEDs) with longer lifetimes of over 10,000 h at 14.5 A/cm2 by introducing an i-ZnMgBeSe/p-ZnMgSe double cladding structure, which includes a very thin i-ZnMgBeSe layer for suppressing electron overflow and a p-ZnMgSSe layer for efficient p-type carrier concentration. By adopting the double cladding layer instead of only the conventional p-ZnMgSSe cladding layer, rapid degradation is suppressed and the lifetime tendency becomes similar to that of the LEDs consisting of a III–V semiconductor system. The device simulation and the temperature dependence of optical power showed that the i-ZnMgBeSe layer played the main role in increasing electron confinement. Our experimental data and reliability test results indicate that the suppression of the electron overflow is essential to achieve a long lifetime acceptable for practical use.

We attempted to prepare Ge1-y C y alloys by implantation of C atoms into Ge crystals and post-annealing. For samples annealed at temperatures higher than 450°C, X-ray diffraction (XRD) spectra indicated that the Ge1-y C y alloys were successfully prepared. The highest substitutional C content was about 1 at.%. The optimum annealing temperature to incorporate C atoms into the substitutional sites was 450–500°C. We also investigated the dependence of the Raman intensity of the Ge–C local mode on the substitutional C content. The intensity of the Ge–C local mode was found to increase in proportion to the substitutional C content. Furthermore, the relationship between Ge–C peak intensity and substitutional C content was relatively in good agreement with that theoretically predicted.

Magnetically induced superresolution (MSR) disks by double masked rear aperture detection (D-RAD) sometimes show direct transition from the initialized state to the D-RAD state in the readout power curves. Peak and trough levels of read signals for these MSR disks were measured and the states of the aperture and the rear mask during the readout were clarified. When the read field is in the erase direction, the aperture opens simultaneously with the collapse of the mark in the rear mask. When the read field is in the write direction, copying a mark from the recording layer to the readout layer starts as the mark in the recording layer overlaps the rear mask and the successive wall displacement copies the mark. The MSR with the latter mechanism was found to be very effective for eliminating crosstalk.

VPE of AlGaAs by the chloride transport method using separate Al and Ga metals has been demonstrated for the first time. AsCl3 instead of toxic AsH3 was used as the arsenic source. Mirror-like surfaces with growth rates of 1–2 µm/hr were obtained. Background doping levels range in the order of 1018 cm-3, probably due to the reaction between AlCl3 and the quartz reactor. Band-edge emissions were observed in the photoluminescence spectra.

GaAs was epitaxially grown at 500–600°C by direct reduction GaCl3 with AsH3/H2. The GaCl3 in a stainless steel evaporator was maintained at about 85°C, and supplied by He carrier gas. The AsH3 diluted with H2 was supplied in a separate line directly to the deposition zone. The growth rate was about 5–10 µm/hr for GaCl3 of 5.5×10-5 mol/min and V/III ratio of 5. The carrier concentrations of the grown layers were 1015 to 1016 cm-3, and the maximum mobility obtained was 10000 cm2/V ·s at 77 K. These results indicate the possibility of a new growth method of III–V compounds.