MULTIPHASES DESCRIPTION OF a-Si : H

Abstract

Photoluminescence, thermally stimulated currents (TSC), optical absorption and electrical conductivity are reported versus deposition temperature and deposition rate of undoped a-Si : H. These results are coherent with a tentative model according to which the radiative recombination and thermal emission take place in a nearly constant and weakly disordered grain like zone, while optical absorption occurs mainly in a widely varying and largely disordered grain boundary like zone ; in this picture, the electrical conductivity involves both zones

Ohmic contacts on sputtered a-Si : H

“…We find room temperature conductivities in the range 10 -9 to 10'~Q.cm'~ with activation energies in the range 0.7 to 0.9 eV rather similar to those found by Paul et al in sputtered films [12] and Solomon et al [4] for glow discharge a-Si : H. With the usually quoted 0.9 to 1 eV [2,13] height for the potential barrier at the intrinsic a-Si : H/Pt interface and -1017 cm-3 recombination centres, we do not expect striking differences between for~•ard and reverse I(V) curves of a-Si/intrinsic a-Si : H/Pt devices. Actually [14], although we find a space charge zone, we do not find rectifying behaviour for such structures, which brings into question the exact role of the n+ a-Si : H/intrinsic a-Si : H function in Schottky diode devices at least in sputtered materials. Schottky behaviour for Pd (a-Si : H interface with n+ a-Si : H) as back contact were reported mainly for glow discharge a-Si : H [2, 3,13].…”

“…Without a semi-log plot of I(V) and its temperature dependence, it is difficult to deduce to what extent these structures exhibit actual Schottky barrier behaviour. Alternatively, almost all these n+ a-Si : H/intrinsic a-Si : H/Metal structures use small a-Si : H thicknesses ( 6 000 A), with the low density of carriers in intrinsic a-Si : H, if the back contacts are not ohmic, the corresponding band bending may be extended almost completely across the film giving I( V) curves similar to those of Schottky diodes [14].…”

Current transport properties of metal/hydrogenated amorphous silicon/GaSb structures

“…Also, n decreased from 2.1 to 1.1. The decrease in the ideality factor and saturation current density with an increase in deposition temperature and after annealing is attributed to the decrease in deep level concentration in bulk a-Si:H. These deep levels originate from the SiH x (xϭ2 or 3͒ centers 12 and are responsible for the Fermi level pinning at the interface. The concentration of SiH x decreases with an increase in deposition temperature.…”

“…The concentration of SiH x decreases with an increase in deposition temperature. 12 Also, SiH x decomposes by annealing at 200-250°C ͑Ref. 12͒ further reducing the deep level concentration.…”

Determination of quasi-Fermi level at the metal–semiconductor interface in a forward-biased schottky barrier diode

“…Therefore, in this case of so-called diffusion theory the electron concentration in the semiconductor a t the metal-semiconductor boundary of a Schot tky barrier diode under forward bias should remain constant, equal to the electron concentration at this boundary when no forward bias is applied to the Schottky diode [6 to 91. This statement is explicitly given in [6]. The same statement is implied in writing equation ( The aim of this work is to obtain the necessary expressions for the position of the electron quasi-Ferini level at the metal-semiconductor boundary of a forward-biased Schottky barrier diode for the cases of constant electron mobility and constant electron velocity.…”