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Poster De Conférence Année : 2015

Influence of surface treatments on the electrical and optical properties of SnO2-Ga2O3 thin films for UV wavelengths applications

Résumé

Ga2O3 is a wide band gap transparent conductive oxide (TCO) currently investigated for Ultra-Violet optroelectronic and photonic devices. In this study, 150nm- thick Ga2O3 - SnO2 layers (with different Sn doping) were grown on (0001) sapphire by MOCVD technique at a pressure of 10 Torr. The substrate temperature was fixed at 700°C. Phase compositions were determined by energy dispersive X-ray spectroscopy (EDX). To enhance the conductivity and transparency of Ga2O3 - SnO2 thin films, the influence of surface treatments was investigated. Subsequent thermal annealing was performed up to 1000 °C, at atmospheric pressure. The optical properties of the annealed samples present a decrease of the band gap which may originate from the contribution to indirect transition and amorphous phase. However, the resistivity remains very large (>108Ω/cm) at all SnO2 concentration. These results indicate that doping is not simply responsible for the conductivity. Vacuum annealing used to change oxygen stoichiometry did not provide any improvements. Transmission electron microscopy (TEM) analyses were carried out on annealed samples. They present a high density of nano-crystalline grains. These phases have particular orientations which are suggested twinning of Ga2O3. If nano-twinning of Ga2O3 is confirmed, that could explain the reduction of carrier’-s’ mobility and provide some explanation about the high resistivity in our films. Meanwhile, Ar+H plasma treatments6 show an increase of conductivity where hydrogen defect may plays a crucial role according to Varley et al.

Domaines

Matériaux
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Dates et versions

hal-01277774 , version 1 (23-02-2016)

Identifiants

  • HAL Id : hal-01277774 , version 1

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Alban Maertens, Samuel Margueron, Frédéric Genty, Ouarda Legrani, Adulfas Abrutis, et al.. Influence of surface treatments on the electrical and optical properties of SnO2-Ga2O3 thin films for UV wavelengths applications. international Conference on Innovation in Thin Film Processing and Characterization, Nov 2015, Nancy, France. . ⟨hal-01277774⟩
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