In this work high gain GaN photoconductive UV detectors have been fabricated and characterized, and a novel gain mechanism, dominant in these detectors, is described. A decrease of both gain and k parameter with temperature has also been observed. As a consequence of the slow non-exponential transient response, AC gain measurements result in lower values for gain and k parameter, which are frequency dependent. Such spatial modulation is due to the photovoltaic response of the potential barriers related to the surface and charged dislocations arrays. Taking into account its superior radiation hardness and high temperature resistance, this material is suitable for devices working in extreme conditions.
Applications range from space communications to ozone layer monitoring or flame detection.
For their simplicity, they are candidates as low cost UV detectors in consumer and environmental applications. Their high responsivity would enable their use without any preamplifier stage. Some of the characteristics of GaN photoconductors have been reported. In this work we present a study of the physical mechanism of photoconductive gain in GaN epitaxial layers, and the computer implementation of a novel model that matches our experimental results quite precisely. This last parameter is determined by the characteristics of the material and the configuration of the detector.