This thesis presents low temperature measurements of photoconductivity in strontium titanate. Results for nominally stoichiometric strontium titanate offer further evidence of a large increase in photocarrier lifetime below ≈ 35 K. Linear photoconductivity is observed suggesting monomolecular recombination is dominant. At still lower temperatures of < 1 K persistent photoconductivity is found to emerge. The non-equilibrium photoconductivity of thin films of oxygen deficient strontium titanate, fabricated by argon irradiation, shows not only persistent photoconductivity, as previously observed in bulk samples but also transient negative photoconductivity. Furthermore large doses of UV exposure are found to induced persistent photoconductivity in stoichiometric strontium titanate. The photocarrier lifetime can be dramatically enhanced by prolonged UV exposure, leading to photoconductivity which persisted on the timescale of hours. Finally results are presented for optically tunable superconducting-semiconducting devices, with the aim of creating Josephson junctions. Although no devices become fully superconducting a potential future route to realising optically tunable Josephson junctions is discussed.
|Date of Award||23 Jan 2019|
- The University of Bristol
|Supervisor||Chris Bell (Supervisor)|