Transport characterisation of group Ⅲ-nitride materials with dominating surface effects

Tamara Fehlberg

    Research output: ThesisDoctoral Thesis

    328 Downloads (Pure)


    [Truncated abstract] Group III-nitride (InN, GaN, AlN) electronics have many important and wide ranging applications, such as high power and high frequency transistors for satellite and mobile communications, solid-state lighting and high efficiency solar power. Performance increases and extension of the device operation regions will be obtained for many III-nitride devices through the incorporation of InN or In-rich InGaN/InAlN to improve transistor speed and move towards longer wavelengths in optical devices, while for high power GaNbased transistor devices, optimising existing passivation materials in transistor designs will enable further performance increases. InN is the least mature of the III-nitride materials. Transport modelling suggests roomtemperature electron mobilities of 12 000 cm2/Vs are possible in low carrier concentration material, however even the highest electron mobilities measured in InN to date are less than a third of that value. The progression towards device quality fims requires improvements in growth and understanding of the doping mechanisms, and this requires the accurate characterisation of the transport properties of the carriers in the material. In this work it is shown that for InN, Hall measurements performed over a range of magnetic fields, with a quantitative mobility spectrum analysis (QMSA), are required to distinguish between the multiple conduction paths that exist in all samples due to the presence of multiple carrier species, which include a native electron surface accumulation and a persistent, high, unintentional background (bulk) n-type doping. This technique greatly improves the accuracy of the characterisation of the bulk electron species, as this work shows that the surface electron species has a signifcant effect on the results obtained through the standard, single magnetic field, Hall characterisation technique. The high unintentional n-type doping is one of the major hurdles in the progression towards
    Original languageEnglish
    QualificationDoctor of Philosophy
    Publication statusUnpublished - 2009


    Dive into the research topics of 'Transport characterisation of group Ⅲ-nitride materials with dominating surface effects'. Together they form a unique fingerprint.

    Cite this