The doping characteristics of a-Si:H films prepared by rf planar magnetron reactive sputtering (MRS) are described. The room-temperature conductivity reaches ca. 1Ω-1 cm-1 at 1000 vppm in the both cases of phosphorus doping and boron doping. MRS a-Si:H films have the doping characteristics similar to GD a-Si:H films. However the maximum conductivity is large compared to GD a-Si:H films, and especially for the boron doping one is large two or three orders of magnitude. The room-temperature conductivity of MRS a-Si:H films depends strongly on the target voltage and the deposition pressure for impurity doping. And also the temperature dependence of conductivity of phosphorus- and boron-doped MRS a-Si:H films are described as a function of dopant concentration. The electronic properties and the densities of gap states of the undoped MRS a-Si:H films are discussed as parameters of hydrogen contents and the ratio of SiH bonds to SiH2 bonds.

Gallium nitride single crystals were grown on (0001) oriented sapphire substrates by metalorganic vapor-phase epitaxy. The films on the initially nitrided sapphire surface showed an uneven surface with prominent hexagonal pyramids, while the films on the non-nitrided sapphire surface exhibited a relatively smooth surface although some fine pits were observed. All the films exhibited n-type conduction with carrier concentrations of 1017-1018 cm-3 and electron mobilities of 30-143 cm2/V sec.

Epitaxial GaN films have been grown on sapphire substrates at 750 by reactive ion plating. GaN film has a direct energy band gap of 3.36 eV. Conductivity, electron concentration and Hall mobility of undoped epitaxial GaN films are 6160 S/cm, 2101811019cm3 and 35100 cm2/Vs, respectively.

A recondary battery utilizing poly(3-methylthiophene) film as a cathode-active meterial in an electrolyte of LiBE4/organic solvent with Al anode was studied. Experimental energy density of 326 Wh/kg (at a doping level of 38%, discharge capacity of 97.3 Ah/kg, and a mean discharging voltage of 3.3 V) was obtained on the weight of the film. The coulombic efficiency was above 96% even after 1200 cycles at a doping level of 9%. The discharge characteristics are described in relation to the surface morphology of the films.