The thickness profiles of GaAs layers grown by electroepitaxy (currentcontrolled liquid phase epitaxy) were investigated in conjunction with experimental growth parameters. It was found that defective electrical contacts to the substrate and variations in the dissolution depth of the substrate by the gallium contact layer lead to random fluctuations in the epitaxial layers. Convective flow in the solution due to horizontal gradients in the solution caused by joule heating leads to systematic variations in the thickness of the epilayers. Experimental procedures are presented for mlmzmzlng or essentially eliminating both types of thickness variations.Current-controlled liquid phase epitaxy, referred to from here on as electroepitaxy, of semiconductors and * Electrochemical Society Active Member. Permanent address: ECL, Nippon Telegraph and Telephone Publie Corporation, Tokyo, Japan.

Flexible devices manufactured using printed electronics have attracted the attention of many researchers. A high-performance transparent conductive film exhibiting high flexibility and elasticity is expected to be developed because of its need for the creation of flexible devices. An indium tin oxide (ITO) thin film, which has generally been used, has weaknesses such as fragility to bending stress and depletion of the resource. This study focused on poly (3, 4-ethylenedioxythiophene)/poly (styrenesulfonate) (PEDOT:PSS), a conductive polymer material, and examined improvement in the resistivity and transmittance of the transparent conductive film produced using an inkjet method. The present study improved the electrical and optical characteristics of the thin film by examining the annealing temperature between printing operations and the application method of a polar solvent. As a result, the resistivity and transmittance of a PEDOT:PSS thin film were 1.49 × 10 −3 Ω•cm and 89.2%, respectively. This film was obtained by annealing at 90˚C for 30 min and applying a polar solvent, using an inkjet printer, between printing operations. The printing was performed three times.

The densification process and canal sealing ability of octacalcium phosphate (OCP)-mediated cement were investigated for developing biocompatible and biodegradable root canal filling material for deciduous root. The results of the characterization revealed that the starting paste, which consisted of monocalcium phosphate monohydrate, calcium carbonate, and α-tricalcium phosphate, gradually transformed into carbonate apatite for 6 weeks of immersion in medium with 30% fetal bovine serum (MEM30). The canal sealing ability was estimated by dye penetration test. Three kinds of conditions were chosen for the test: one was the cement just after filling the single-rooted extracted human roots; the others were the cement aged in MEM30 for 1 and 6 weeks after filling, respectively. All roots were then immersed in India ink for 3 days. The penetration depth of OCP-mediated cement decreased significantly with time. This demonstrates that OCP-mediated cement has self-sealing ability.

It was found that terraces commonly present on GaAs layers grown by standard (thermal) LPE were not present on layers grown by electroepitaxy. A

A comparative study was carried out on the defect structure and electronic properties of normalGaAs layers grown under similar conditions by electroepitaxy (electromigration controlled) and by thermal LPE. It was found that the density of certain microdefects, commonly present in normalGaAs layers, is significantly smaller (about an order of magnitude) in electroepitaxially grown than in thermally grown layers. It was also found that electroepitaxial layers exhibit greater carrier mobility and diffusion length than the thermally grown layers; in addition, electroepitaxially grown p‐n junctions exhibited lower saturation current than the thermally grown junctions. The differences in the characteristics of two types of layers are attributed to corresponding differences in the nature of the driving forces for growth.