Semiconductor barrier modification

A surface barrier to the transfer of holes will arise if a positive surface charge is established on a P-type semiconductor, i.e., a semiconductor in which holes are the electrical current carriers. With such a surface charge the bands will bend down. Effects occurring on a P-type semiconductor will not be discussed explicitly in this article, although the same general principles apply with minor modifications. 

Zeolite membranes and films have been employed to modify the surface of conventional chemical electrodes, or to conform different types of zeolite-based physical sensors [49]. In quartz crystal microbalances, zeolites are used to sense ethanol, NO, SO2 and water. Cantilever-based sensors can also be fabricated with zeolites as humidity sensors. The modification of the dielectric constant of zeolites by gas adsorption is also used in zeolite-coated interdigitaled capacitors for sensing n-butane, NH3, NO and CO. Finally, zeolite films can be used as barriers (for ethanol, alkanes,...) for increasing the selectivity of both semiconductor gas sensors (e.g. to CO, NO2, H2) and optical chemical sensors. 

This work is devoted to investigation of the effect of texturing organic/ inorganic semiconductor interfaces on the optical, photoelectric and electrical properties of barrier OS/GaAs heterostructures in search of the more efficient method of the OS/IS interfaces modification for the enhancement of the heterostructure photosensitivity. 

The absence of solvents in such solid-polymer-electrolyte photovoltaic cells presents the possibility of fabricating corrosion-free systems. The thin-film solid-state cells also allow fabrication of multispectral cells composed of more than one semiconductor in optical and electrical series. A solid-state photovoltaic cell, n-Si/Pt/PP/PEO(K.I/ l2)/Pt/ITO, was studied. The surface modifications of n-Si with PP can dramatically reduce the large activation energy barrier against efficient charge transfer between semiconductor and polymer-solid electrolyte. The efficiency of this cell is limited by a high surface recombination velocity associated with surface states of the n-Si. The cell had V = 225 mV and 11 niA cm at 100 mW cm illumination with junction ideality factor of 1.5. This implies the existence of deleterious surface states acting as recombination centres. 

---