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Triethylsilylethynyl anthradithiophene (TESADT) holds considerable promise for organic transistor applications due to the high electrical mobilities attained by post-deposition crystallisation using solvent vapour annealing. We have studied thermal annealing as an alternative route to post-deposition crystallisation of TESADTfilms. Thermal annealing initially appears promising, producing mm-sized crystal domains, but poor electrical performance is obtained, which we attribute to a combination of crack formation and potentially also a structural transition during the anneal process. We also find that illumination has a significant positive effect on crystallisation, possibly due to an optically induced enhancement in molecular mobility during annealing. This suggests that further studies of how solvent exposure, heat, substrate surface properties and particularly light exposure influence the ordering kinetics of TESADTare warranted.

We measure the dependence of the phase breaking time on temperature and on dc voltage in ballistic split-gate quantum dots, the lead openings of which are defined by means of quantum point contacts. Estimates for the phase breaking time are obtained by studying the high-field evolution of the reproducible fluctuations, observed in the low-temperature magneto-conductance of the devices, and from the quenching of quantum interference induced by the dc bias. Varying either temperature or dc bias, a saturation of the phase breaking time is observed for sufficiently low values of these parameters. The energy scale at which the saturation onsets is found to be comparable to the average spacing of discrete levels within the quantum dot, indicative of a crossover to zero-dimensional phase breaking. Based on these observations, we suggest that studies of electron phase coherence may provide a powerful probe of the intrinsic eigenspectra of open quantum dots.

We present investigations of the fractal behaviour of magneto-conductance fluctuations in semiconductor billiards as a function of temperature. The introduction of finite phase coherence by nonzero temperatures is found not to suppress fractal behaviour in the experimental data. Instead, we show that the fractal dimension decreases with increasing temperature and we present a remarkable similarity between the phase coherence time and the fractal dimension.

We show that self-similar magneto-conductance fluctuations observed in semiconductor Sinai billiards originate from quantum interference processes, which are associated with classical trajectories that enclose discrete areas. We identify the exact areal distributions and reproduce the self-similarity with remarkable accuracy.