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We report on the hydrothermal growth of high quality arrays of single crystalline zinc oxide (ZnO) nanocolumns, oriented perpendicularly to the transparent conductive oxide substrate. In order to obtain precisely defined spacing and arrangement of ZnO nanocolumns over an area up to 0.5 cm 2 , we used electron beam lithography. Vertically aligned ZnO (multicrystalline or single crystals) nanocolumns were grown in an aqueous solution of zinc nitrate hexahydrate and hexamethylenetetramine at 95 °C, with a growth rate 0.5 ÷ 1 μm/h. The morphology of the nanostructures was visualized by scanning electron microscopy. Such nanostructured ZnO films were used as a substrate for the recently developed 3-dimensional thin film silicon (amorphous, microcrystalline) solar cell, with a high efficiency potential. The photoelectrical and optical properties of the ZnO nanocolumns and the silicon absorber layers of these type nanostructured solar cells were investigated in details.

In this paper we have shown that it is possible to modify and control the surface morphology of doped SnO2 transparent conducting oxide thin films deposited by atmospheric pressure Chemical Vapour Deposition by use of additives during the deposition process. A range of volatile organic compounds were explored, which caused changes of differing magnitude to the growth rates, crystallographic preferences, size and shape of the surface features and optical transmittance. Of the additives tested methanol and tertiary butanol were found to have the most significant influence allowing the surface to be modified from small, round features to much more elongated, sharp, pyramidal features.

Two technological strategies to generate patterned diamond growth have been tested. The diamond micro-structures (i.e. linear stripes and 5 µm narrow channels) were grown in the thickness of 450 nm on Si/SiO 2 substrates by a microwave plasma chemical vapor deposition process. Strategy 1, employing a metal mask, resulted in unsatisfying patterned diamond growth due to instability of metal mask. Strategy 2 was based on a direct lithographic patterning of the seeding layer and resulted in a strongly selective, homogenous, and compact growth of diamond on the polymer-coated seeding patterns. This is assigned to the high seeding yield. The diamond micro-structures formed in this way exhibit surface conductivity of 10 − 7 (Ω/□) − 1 as assessed by I – V characteristics. The observed results appear promising for the development of directly grown diamond-based transistors.

The potential of thin film photovoltaic technologies in supporting sustainable energy policies has led to increasing interest in high performance transparent conducting oxides (TCOs), and in particular doped SnO2, as electrical contacts for solar cells. We have developed an advanced atmospheric pressure chemical vapour deposition process, by applying fast experimentation and using a combinatorial chemistry approach to aid the studies. The deposited films were characterised for crystallinity, morphology (roughness) and resistance to aid optimisation of material suitable for solar cells. Optical measurements on these samples showed low absorption losses, less than 1% around 500 nm for 1 pass, which is much lower than those of industrially available TCOs. Selected samples were then used for manufacturing single amorphous silicon (a-Si:H) solar cells, which showed high solar energy conversion efficiencies up to 8.2% and high short circuit currents of 16 mA/cm2. Compared with (commercially available) TCO glasses coated by chemical vapour deposition, our TCO coatings show excellent performance resulting in a high quantum efficiency yield for a- Si:H solar cells.

Steady state and low frequency photocurrent spectroscopies have proved as a valuable tool for investigation of many different semiconductors, used for example as an absorber in photovoltaic solar cells or in the large area sensors. Fourier transform photocurrent spectroscopy (FTPS), described here, exhibits advantages as a high sensitivity (we demonstrate dynamical range up to 9 orders of magnitude of the optical absorption coefficient, connected with the absorption process leading to free carriers; or sensitivity for dopant detection better than 1 part-per-billion), fast acquisition of data (it can be of the order of seconds) or high resolution (under more lengthy acquisition of data). Results on amorphous silicon, microcrystalline silicon, diamond layers, nanocrystalline diamond and very thin organic films, as poly(2-methoxy-5-(3′,7′-dimethyl-octyloxy))-p-phenylene-vinylene (MDMO-PPV), regioregular poly(3-hexylthiophene (P3HT) and their blends with (6,6)-phenyl-C61-butyric-acid (PCBM) are reported, together with the results measured on various thin film silicon or polymer solar cells.

SnO2 thin films, is compatible with industrial requirements such as high process speed, scaling to wide substrate widths and low costs. Precise method for measuring the optical absorptance in the spectral range 300–1700 nm combines transmittance, reflectance and photothermal deflection (PDS) spectra measured on the same spot of the sample immersed in the transparent liquid with a relatively high index of refraction. The effects of the film thickness, doping gas addition and the susceptor temperature on the optical absorptance and electrical resistivity of the TCO films are assessed. We show that the doping gas concentration and the susceptor temperature influence both the incorporation ratio of dopants into SnO2 film as well as the defect concentration. The SnO2 films growth at optimum APCVD conditions have thickness 0.7 μm, average surface roughness about 40 nm, sheet electrical resistance 10 Ω/sq and the optical absorption 1% at 500 nm and about 5% at 1000 nm.