ALTERNATIVE DOPED A-SI1-XCX-H AND NC-SI1-XCX-H FILMS

Conductive amorphous and nanocrystalline films were prepared from gas mixtures containing the dopant vapor (P(CH3)(3) or B(C2H5)(3)), silane and hydrogen by use of a lambda/4 helical resonator plasma source ope rating at 40 MHz. Film microstructure was observed by atomic force mic roscopy (AFM) and ultraviolet reflectometry. Secondary ion mass spectr ometry (SIMS) and electron probe micro analysis (EPMA) was used to inv estigate the film composition. Measurements of transmission and reflec tion were done to determine the film thickness, refractive index and t he Tauc optical gap. The maximum dark conductivity was about 0.5 to 1 S/cm with an activation energy of about 50 meV. Dangling bond densitie s were estimated by constant photocurrent method (CPM). Electron and h ole diffusion lengths determined by the dynamic interference grating ( DIG) method are found to be sensitive to the type of conductivity and to the density of dangling bonds. A two-color sensor with a n-i-p-i-n layer sequence was fabricated as an illustration to the application of the alternative doping technique based on liquid sources P(CH3)(3) an d B(C2H5)(3). (C) 1998 Elsevier Science B.V. All rights reserved.