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Total photoyield spectroscopy (TPYS) measurement is applied to boron (B)-doped polycrystalline diamond, which shows an extremely low cathode fall voltage (Vc) in glow discharge operation. The B-doped diamond film grown on a molybdenum (Mo) substrate shows Vc of about 43 V after hydrogenation with a small amount of hydrogen added to argon (Ar + 0.03% H2). This Vc value is almost 1/3 that of the Mo substrate without diamond. The TPY spectrum of the diamond after hydrogenation in microwave hydrogen plasma shows obvious onset at 4.5 eV, which is below the band-gap energy of diamond (5.47 eV). This is attributed to the negative electron affinity (NEA), which results in an electron affinity of −1.0 eV. Vc and TPY spectra are also measured for acid treatment condition and Mo. From these experiments, the low Vc values of B-doped polycrystalline diamond depending on the surface treatment correlate to the difference between electron affinities derived from the TPYS measurements.

We fabricate planarized carbon nanotube (CNT) via interconnects using chemical mechanical polishing (CMP). The selective growth of CNT bundles in via holes and the filling of spin-on-glass into the space among the CNTs are performed, followed by a CMP process. The via resistance is reduced by post-CMP treatment and post-annealing due to the improvement in the top contact formation. The measured CNT via resistance is higher than the CNT bundle resistance estimated from the measured resistance of an individual CNT. This indicates that contact resistance is higher than the CNT resistance in the CNT via interconnect.

We report on the electrical properties of carbon nanotube (CNT) via interconnects with improvement in contact formations between the CNT via and metal electrodes. For the improvement of the bottom contact formation, a TiN/TaN multilayer on a Cu bottom wiring layer is applied to suppress formation of a highly resistive oxide layer on the TaN barrier layer. The top electrode formation with good coverage on CNTs reduces contact resistance. The current–voltage characteristics of ultrafine CNT via interconnects exhibit ohmic behavior. The resistance of the CNT via interconnect is inversely proportional to the via area, indicating that the CNT bundles are grown with uniform quality and density in various-diameter via holes.

Carbon nanotubes (CNTs) have been grown by surface-wave plasma-enhanced chemical vapor deposition (CVD) using size-classified Co nanoparticles at low temperatures. A mesh grid is used in the remote plasma-enhanced CVD system for the suppression of ion bombardment damage from plasma. The control of the electric field distribution using a mesh grid with a narrower opening is effective for the CNT growth. Multiwalled CNTs are obtained at a low temperature of 400 °C under low ion-density conditions. No significant difference in the microscopic structure of the CNTs grown at temperatures between 400 and 500 °C is observed.

The characteristics of Mg-doped GaN and AlGaN grown by H2-ambient and N2-ambient metalorganic chemical vapor deposition are compared and discussed. While as-grown Mg-doped GaN and AlGaN grown under H2-ambient show high resistivity, p-type GaN and AlGaN with high acceptor concentration were obtained by N2-ambient growth without any post-treatment. The hydrogenation process of the Mg acceptor and the dissociation process of hydrogen atoms from Mg–H complexes might occur simultaneously in the case of N2-ambient growth. The films grown under N2-ambient were clearly shown to have superior characteristics in uniformity and reproducibility to those grown under H2-ambient, since the characteristics of the films grown under N2-ambient are steady over the wide range of growth temperature. Our results indicate that the N2-ambient growth is suitable for the mass production of GaN-based light-emitting devices in the respects that the device fabrication process can be simplified and that the uniformity and the reproducibility of the layer properties are greatly improved.

We demonstrate room temperature pulsed operation of nitride based multi-quantum-well (MQW) laser diodes with cleaved mirror facets grown on a conventional C-face sapphire substrate. Cleavage was performed along the direction of the sapphire substrate, and the resultant facet was analyzed using an atomic force microscope (AFM) and theoretical calculation. A single peak emisson, at a wavelength of 417.5 nm, with a full width at half-maximum of 0.15 nm, was obtained. The threshold current density of the laser was 50 kA/cm2 and a voltage for the threshold current was 20 V.

High-concentration, low-resistivity p-type Zn-doped InAlP alloy layers were achieved using metalorganic chemical vapor deposition (MOCVD) and off-axis substrates. The highest net acceptor concentration (N A-N D=1.3×1018 cm-3), obtained using an off-axis substrate, is one order of magnitude higher than the previously reported maximum value. Substrate misorientation was found to improve the Zn electrical activity in addition to the enhancement of Zn incorporation efficiency. Electrical resistivities as low as 0.68 Ω ·cm were obtained. High device performance was obtained for 630 nm band laser diodes (LDs) and green light emitting diodes (LEDs) fabricated with the highly Zn-doped InAlP as the p-type cladding layers.