Radiative recombination of confined electrons at the MgZnO/ZnO heterojunction interface

We investigate the optical signature of the interface in a single MgZnO/ZnO heterojunction, which exhibits two orders of magnitude lower resistivity and 10 times higher electron mobility compared with the MgZnO/Al2O3 film grown under the same conditions. These impressive transport properties are attributed to increased mobility of electrons at the MgZnO/ZnO heterojunction interface. Depth-resolved cathodoluminescence and photoluminescence studies reveal a 3.2 eV H-band optical emission from the heterointerface, which exhibits excitonic properties and a localization energy of 19.6 meV. The emission is attributed to band-bending due to the polarization discontinuity at the interface, which leads to formation of a triangular quantum well and localized excitons by electrostatic coupling

Random lasing in high quality ZnO thin films

International audienc

Studies of Optical Emission in the High Intensity Pumping Regime for Top Down ZnO Nanostructures Grown on c-Sapphire Substrates by Pulsed Laser Deposition

International audienc

Studies of Optical Emission in the High Intensity Pumping Regime for Top Down ZnO Nanostructures Grown on c-Sapphire Substrates by Pulsed Laser Deposition

International audienc

Studies of Optical Emission in the High Intensity Pumping Regime for Top Down ZnO Nanostructures Grown on c-Sapphire Substrates by Pulsed Laser Deposition

International audienc

Study of Au coated ZnO nanoarrays for surface enhanced Raman scattering chemical sensing

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Microstrip Array Ring FETs with 2D p-Ga2O3 Channels Grown by MOCVD

Gallium oxide (Ga2O3) thin films of various thicknesses were grown on sapphire (0001) substrates by metal organic chemical vapor deposition (MOCVD) using trimethylgallium (TMGa), high purity deionized water, and silane (SiH4) as gallium, oxygen, and silicon precursors, respectively. N2 was used as carrier gas. Hall measurements revealed that films grown with a lower VI/III ratio had a dominant p-type conduction with room temperature mobilities up to 7 cm2/Vs and carrier concentrations up to ~1020 cm−3 for thinner layers. High resolution transmission electron microscopy suggested that the layers were mainly κ phase. Microstrip field-effect transistors (FETs) were fabricated using 2D p-type Ga2O3:Si, channels. They achieved a maximum drain current of 2.19 mA and an on/off ratio as high as ~108. A phenomenological model for the p-type conduction was also presented. As the first demonstration of a p-type Ga2O3, this work represents a significant advance which is state of the art, which would allow the fabrication of p-n junction based devices which could be smaller/thinner and bring both cost (more devices/wafer and less growth time) and operating speed (due to miniaturization) advantages. Moreover, the first scaling down to 2D device channels opens the prospect of faster devices and improved heat evacuation

Etudes de nanostructures de ZnO

International audienc

Microstrip Array Ring FETs with 2D p-Ga₂O₃ Channels Grown by MOCVD

Gallium oxide (Ga2O3) thin films of various thicknesses were grown on sapphire (0001) substrates by metal organic chemical vapor deposition (MOCVD) using trimethylgallium (TMGa), high purity deionized water, and silane (SiH4) as gallium, oxygen, and silicon precursors, respectively. N2 was used as carrier gas. Hall measurements revealed that films grown with a lower VI/III ratio had a dominant p-type conduction with room temperature mobilities up to 7 cm2/Vs and carrier concentrations up to ~1020 cm−3 for thinner layers. High resolution transmission electron microscopy suggested that the layers were mainly κ phase. Microstrip field-effect transistors (FETs) were fabricated using 2D p-type Ga2O3:Si, channels. They achieved a maximum drain current of 2.19 mA and an on/off ratio as high as ~108. A phenomenological model for the p-type conduction was also presented. As the first demonstration of a p-type Ga2O3, this work represents a significant advance which is state of the art, which would allow the fabrication of p-n junction based devices which could be smaller/thinner and bring both cost (more devices/wafer and less growth time) and operating speed (due to miniaturization) advantages. Moreover, the first scaling down to 2D device channels opens the prospect of faster devices and improved heat evacuation

Preparation and Characterization of β-Ga₂O₃-based Photo detectors for UV Detection Applications

International audienceCompact photodetectors with a significant response in the UVC spectral band (100-280 nm) present a growing interest since of their potential applications to "New Space" nanosatellite constellation missions. Gallium oxide, with an already intrinsic ultra wide bandgap of 4.9 eV at 253 nm, can be engineered further into the ultraviolet (UV) by alloying it with Al. This next generation of MUV (200-300 nm) photodetectors is uniquely suitable for solar radiation from Space, and specifically the Herzberg continuum (200-242nm) that plays an important role in regional climate change through interactions with stratospheric ozone. This work presents the photolithographic, packaging and characterization of β-Ga 2 O 3-based photodetectors destined to study and improve our understanding of the solar UV impact on the Earth's climate. Different tests are used to confirm the final selection of protoflight detectors, such as photo-electric performance, photoresponse time and thermal cycle studies. These detectors are then projected to be integrated on a nanosatellite (INSPIRE-Sat 7, a "2U" cubesat) to be launched in early 2023 to monitor the absolute solar spectral irradiance and variability in the Herzberg continuum to better understand the stratospheric ozone response to solar UV irradiance changes. Results suggest that β-Ga 2 O 3-based photodetectors may certainly be a promising candidate for optoelectronic applications in the UV-detection for its high responsivity and low dark current, "solar-blindness above 250 nm" and radiation hard properties. Thermal influence, photo-responsivity and response time are reported