Effects of beta radiation on nanostructured semiconductor devices for low energy radiation sensing

Abstract

Beta radiation detection currently relies primarily on scintillation detectors. However, the construction of these detectors tends to be large which significantly limits their applicability for field-use. A nanostructured Pt/TiO2/Ti Schottky device was constructed for use as a compact, low energy radiation detector by making use of surface plasmon resonance which has been shown to enhance energy coupling in similar technologies. The fabrication of the device was done by first electrochemically anodizing a titanium substrate to create a nanoporous surface, followed by annealing to produce a crystalline, semiconducting TiO2 layer and finally the deposition of the Pt Schottky metal through atomic layer deposition. Modeling of the device using COMSOL software showed the formation of strong electric fields when nanostructures were present. Exposure of the device to low energy 63Ni beta radiation showed a 2-to-3-fold increase to the forward current during radiation exposure without any additional signal amplification. This increase in the current is a consequence of a 2 to 4 percent lowering of the Schottky barrier height during radiation exposure as well as the production of hot and secondary electrons in the semiconductor. Subsequent improvements to the device using rapid thermal annealing resulted in a nearly 6 percent decrease of the Schottky barrier height during radiation exposure and a consequent 5-fold increase to the forward bias current in the presence of radiation. Thus, in its current construction the device is capable of being used as a qualitative low energy beta radiation detector.