Description:
<jats:p> Two-dimensional (2D) semiconductor materials like Transition Metal Dichalcogenides (TMDCs) are prominent candidates to replace silicon (Si) as channel material in the future (Si-based) transistors. However, to fully exploit the superior properties of 2D TMDCs, their inherent problem of basal-plane inertness needs to be resolved to enable dielectric passivation layer growth. Therefore, the objective of this work is to explore innovative options to enable high-k growth on 2D materials.</jats:p>
<jats:p>A literature study is provided, setting out how 2D materials became of interest to the microelectronic industry as a results of continuous device downscaling. To overcome the issue of basal plane inertness, a single layer graphene is used that acts as a sacrificial growth template. This graphene layer is deposited on top of a base layer (e.g. 2D material), whereby the graphene layer is chemically activated via a dry UV/ozone treatment, while preserving the properties of the underlying 2D layer.</jats:p>
<jats:p>Initial experiments focus on the removal of polymer-based transfer residues that typically remain on the graphene surface after transfer. Mechanical scratching atomic force microscopy shows that hydrogen plasma treatments are an effective and time-efficient method to remove polymer transfer residues. However, the plasma exposure also induces surface modifications as demonstrated by Raman characterization.</jats:p>
<jats:p>Next, the growth template is chemically activated by gently oxidizing the graphene layer via a dry UV/ozone treatment. The UV/ozone process characteristics are explored in function of the graphene cleaning treatments developed in the previous stage. For as-received graphene an operating window of 2-5 minutes of UV/ozone exposure is defined in order to maximize the oxidation degree, and thus nucleation sites. Activation is in balance with graphene layer damage or removal. The process is evaluated based on contact angle measurements, Raman and conductivity atomic force microscopy characterization.</jats:p>
<jats:p>Lastly, an atomic layer deposition study is carried out that focuses on high-k deposition on the activated single layer graphene to provide a proof-of-concept of enhanced dielectric growth in function cleaning and activation treatments developed in the preceding stages. Rutherford backscattering spectroscopy demonstrates the importance of a well-functionalized surface to achieve good material growth. </jats:p>