title: Submicrometre resolved optical characterization of green nanowire-based light emitting diodes.
abstract: The electroluminescent properties of InGaN/GaN nanowire-based light emitting diodes (LEDs) are studied at different resolution scales. Axial one-dimensional heterostructures were grown by plasma-assisted molecular beam epitaxy (PAMBE) directly on a silicon (111) substrate and consist of the following sequentially deposited layers: n-type GaN, three undoped InGaN/GaN quantum wells, p-type AlGaN electron blocking layer and p-type GaN. From the macroscopic point of view, the devices emit light in the green spectral range (around 550 nm) under electrical injection. At 100 mA DC current, a 1 mm2 chip that integrates around 10(7) nanowires emits an output power on the order of 10 µW. However, the emission of the nanowire-based LED shows a spotty and polychromatic emission. By using a confocal microscope, we have been able to improve the spatial resolution of the optical characterizations down to the submicrometre scale that can be assessed to a single nanowire. Detailed μ-electroluminescent characterization (emission wavelength and output power) over a representative number of single nanowires provides new insights into the vertically integrated nanowire-based LED operation. By combining both μ-electroluminescent and μ-photoluminescent excitation, we have experimentally shown that electrical injection failure is the major source of losses in these nanowire-based LEDs.
authors.affiliation: CEA-LETI, MINATEC Campus, 17 avenue des Martyrs, 38054 Grenoble Cedex 9, France.
authors.forename: A L
authors.initials: AL
authors.lastname: Bavencove
authors.forename: G
authors.initials: G
authors.lastname: Tourbot
authors.forename: J
authors.initials: J
authors.lastname: Garcia
authors.forename: Y
authors.initials: Y
authors.lastname: Désières
authors.forename: P
authors.initials: P
authors.lastname: Gilet
authors.forename: F
authors.initials: F
authors.lastname: Levy
authors.forename: B
authors.initials: B
authors.lastname: André
authors.forename: B
authors.initials: B
authors.lastname: Gayral
authors.forename: B
authors.initials: B
authors.lastname: Daudin
authors.forename: Le Si
authors.initials: le S
authors.lastname: Dang