Semi‐transparent pn‐heterojunctions were fabricated from pulsed laser deposited (PLD) n‐type ZnO and DC magnetron sputtered p‐type NiO, working as UV‐active solar cells. The complete cell stack has an average transmission of 46% in the visible spectral range and an optical absorption edge at 380 nm. The diodes exhibit high current rectification of up to eight orders of magnitude at ±2 V. Upon illumination with a solar simulator, the devices show photovoltaic activity with open‐circuit voltages of up to 520 mV, short‐circuit current densities of 0.5 mAcm2, and a maximum external quantum efficiency of 55%. However, we observed rather low fill factors of the current–voltage characteristics of around 40%, resulting in total power conversion efficiencies of around 0.1% and efficiencies in the UV range of 3.1%. To identify possible loss mechanisms, the voltage‐dependent efficiency of carrier collection was calculated. The data were fitted using a model that considers recombination losses at the NiO/ZnO interface as well as within the electric field region, yielding a high hole interface recombination velocity of 1×105cm s−1. We conclude that the carrier collection efficiency is strongly deteriorated by recombination losses at the NiO/ZnO interface, causing a strong bending of the jV characteristics under illumination and thereby low fill factors.

A concept for detection of charged particles in a single fly-by, e.g. within an ion optical system for deterministic implantation, is presented. It is based on recording the image charge signal of ions moving through a detector, comprising a set of cylindrical electrodes. This work describes theoretical and practical aspects of image charge detection (ICD) and detector design and its application in the context of real time ion detection. It is shown how false positive detections are excluded reliably, although the signal-to-noise ratio is far too low for time-domain analysis. This is achieved by applying a signal threshold detection scheme in the frequency domain, which - complemented by the development of specialised low-noise preamplifier electronics - will be the key to developing single ion image charge detection for deterministic implantation.

For the engineering of nitrogen-vacancy (NV) centers in diamond, vacancies have been introduced locally into a type Ib diamond (100–200 ppm nitrogen content) by implanting argon ions from a sub-500 nm focused beam. At an acceleration potential of 12 kV, different charge states (Ar n+, n={1,4,8,11}) result in kinetic energies of 12–132 keV. NV-centers were formed by a subsequent annealing step. A wide range of fluences from around one ion to several hundred ions was implanted per spot. It was found that, on average, between 0.04 (12 keV) and 0.79 (132 keV) NV-centers are created from the vacancies of a single implanted argon ion, depending on the ion energy, but not on the fluence. The different number of vacancies created at each energy alone cannot account for the difference in NV-center yield. However, the probability of a given vacancy to diffuse to the diamond surface during annealing, where it cannot contribute to NV-center formation, was simulated and can fully explain the NV-yield behavior. With this model, an upper bound of approximately 300 nm for the diffusion length of a single vacancy was found for an annealing temperature of 800 °C.

Image charge detection is a non-perturbative pre-detection approach for deterministic ion implantation. Using low energy ion bunches as a model system for highly charged single ions, we experimentally studied the error and detection rates of an image charge detector setup. The probability density functions of the signal amplitudes in the Fourier spectrum can be modelled with a generalised gamma distribution to predict error and detection rates. It is shown that the false positive error rate can be minimised at the cost of detection rate, but this does not impair the fidelity of a deterministic implantation process. Independent of the ion species, at a signal-to-noise ratio of 2, a false positive error rate of 0.1% is achieved, while the detection rate is about 22%.