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Graphene GaN-based Schottky ultraviolet detectors are fabricated. The monolayer graphene is grown by chemical vapor deposition. The graphene is much more transparent than metals, as confirmed by the fact that our devices retain their high responsivity up to 360-nm wavelength (corresponding to the band edge absorption of GaN). Importantly, by virtue of the tunable work function of graphene, the graphene GaN Schottky barrier height can be greatly enlarged. The built-in field is enhanced, and the detector performance is improved. The current ratio with and without luminescence is up to 1.6\times 10^4 . The characteristic time constants of the devices are in the order of a few milliseconds. The device open-circuit voltage and short-circuit current are also increased. At last, special type Schottky devices consisting of GaN nanorods or surface-etched GaN are prepared for complementary study. It is found although the dry etching induced surface defects lead to an increase in the dark current, and these carrier traps also greatly contribute to the photoconductivity under luminescence, resulting in extraordinarily large responsivity (up to 360 A/W at −6 V). [ABSTRACT FROM AUTHOR]

Ordered and dense GaN light emitting nanorods are studied with polycrystalline graphene grown by rapid chemical vapor deposition as suspended transparent electrodes. As the substitute of indium tin oxide, the graphene avoids complex processing to fill up the gaps between nanorods and subsequent surface flattening and offers high conductivity to improve the carrier injection. The as-fabricated devices have 32% improvement in light output power compared to conventional planar GaN-graphene diodes. The suspended graphene remains electrically stable up to 300 °C in air. The graphene can be obtained at low cost and high efficiency, indicating its high potential in future applications. [ABSTRACT FROM AUTHOR]

In this paper, by virtue of one-dimensional ZnO nanorods and two-dimensional graphene film hybrid structures, both the enhanced current spreading and enhanced light extraction were realized at the same time. A 1 nm/1 nm Ni/Au layer was used as an interlayer between graphene and pGaN to form ohmic contact, which makes the device have a good forward conduction properties. Through the comparison of the two groups of making ZnO nanorods or not, it was found that the 30% light extraction efficiency of the device was improved by using the ZnO nanorods. By analysis key parameters of two groups such as the turn-on voltage, work voltage and reverse leakage current, it was proved that the method for preparing surface nano structure by hydrothermal method self-organization growth ZnO nanorods applied in GaN LEDs has no influence to device’s electrical properties. The hybrid structure application in GaN LED, make an achievement of a good ohmic contact, no use of ITO and enhancement of light extraction at the same time, meanwhile it does not change the device structure, introduce additional process, worsen the electrical properties. [ABSTRACT FROM AUTHOR]