Thin-film transistors (TFTs) were fabricated on polycrystalline silicon (poly-Si) films formed by position-controlled largegrain growth technology using an excimer laser. The field-effect mobility, on-off transition slope, and threshold voltage were 914 cm 2 V À1 s À1 , 93 mV/decade, and 0.58 V for the n-channel device, and 254 cm 2 V À1 s À1 , 122 mV/decade, and À0:43 V for the p-channel device, respectively. These values indicate that TFTs had an ultrahigh performance comparable to that of {100}-oriented crystal-silicon metal-oxide-semiconductor (MOS) transistors. Furthermore, their effective mobilities had the same effective field and temperature dependences as those of MOS transistors, indicating that electrons and holes were predominantly scattered not by random grain boundaries or defects in the Si film, but by phonons at the SiO 2 -Si interface, similarly to those of crystal-silicon MOS transistors. These attractive results were obtained as a result of the fact that the TFT channel region was made up of nearly {100}-oriented single grains.

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Drain bias dependence of threshold voltages of short channel thin-film transistors (TFTs) fabricated on polycrystalline silicon (poly-Si) films with large grains has been investigated. The drain coefficient of the threshold voltage was found to be substantially larger in poly-Si TFTs than that in metal-oxide-semiconductor field-effect transistors on a silicon-on-insulator wafer. In addition, the drain coefficient of poly-Si TFTs shows asymmetric behavior with respect to source-drain swapping. The observed results can be explained in terms of body potential modulation caused by accumulation of excess holes generated by impact ionization and drain junction leakage. The asymmetry in drain coefficient with source-drain swapping can be attributed to the difference in the bipolar gain between the source-body and drain-body junctions.

The formation process of the superconducting phases from the rapidly quenched Bi2−xPbxCa2Sr2Cu3Ow (0≤x≤0.4) glasses has been studied as a function of both heat treatment temperature and time. The temperature-time-transformation (T-T-T) diagrams constructed for the glasses greatly depend on the Pb content. The formation region of Ca2PbO4, which may play an important role in producing the 110 K phase, is very wide in the T-T-T diagrams of Pb-rich samples.

The characteristics of thin-film transistors (TFTs) fabricated on pseudo-single-crystal (PSX)-Si thin films were examined. The variations of mobility were more than the theoretical values derived from the crystallographic orientation dependence of a bulk Si metal–oxide–semiconductor (MOS) transistor. To clarify the origin of this discrepancy, the relationships between the TFT characteristics and the crystallographic orientation of Si films in the channel region were investigated by using an electron backscattering pattern (EBSP) method. It was found that the surface orientation dependence for the PSX-Si TFT was different from that for a bulk Si MOS transistor, especially for the p-channel mode. A group of TFTs having a nearly {100}-oriented nucleus had a mobility close to those of simultaneously processed silicon-on-insulator (SOI) devices in the p-channel mode as well as in the n-channel mode. In contrast, a group of TFTs having a nearly {110}-oriented nucleus had a low and widely scattered mobility. The reason for these results is that twin boundaries with dislocations are easily generated in a grain grown from a {110}-oriented nucleus in order to compensate for the difference of the growth rates in different directions.