Project title: Hafnium oxide/graphene hybrid thin-films detector for X-ray imaging - an innovative concept for X-ray detection technology
Acronym: HafGraphX
Project type: PNCDI IV - Program 5.7 - Partnership for Innovation (integral), Subprogram 5.7.1 Partnerships for competitiveness. Experimental Demonstration Project
Contract no. 10PED/2025 (code PN-IV-P7-7.1-PED-2024-0788)
Project duration: 03/01/2025 - 31/12/2026.
Budget: 778.750 Lei (750.000 lei from the state budget and 28.750 lei co-financing)
Contracting Authority: Executive Agency for Higher Education, Research, Development and Innovation Funding – UEFISCDI (www.uefiscdi.gov.ro)
Coordinator: National Institute for Research and Development in Microtechnologies – IMT Bucharest (www.imt.ro)
Project manager: : Dr. Florin Năstase (florin.nastase@imt.ro)
Partner: DOSITRACKER SRL
Responsible partner: Dr. Codruț Cheresteș (codrut.cherestes@dositracker.com)

The characteristics of commercial X-ray flat-panel detectors are now approaching the maximum values provided by the present technological concept. New architectures and new materials are required to overcome the present limitations. In this context, an X-ray sensor based on   hafnium oxide/graphene hybrid thin-films structures may be an innovative concept for X-ray detection technology. Due to these requirements, graphene has been selected for photodetection. To achieve the thin film scintillation layer hafnium was chosen due to the fact that is one of heavy atoms, the necessary feature for high absorption of X-rays in a thin layer. The central purpose of the project is to develop an X-ray sensor based of hafnium oxide as scintillator and graphene as photodetector element for potential applications in X-ray flat-panel detectors. A first objective of the project is to experimental research of X-ray luminescence capabilities of hafnium oxide thin films grown by atomic layer deposition (ALD) deposition technique. The second objective are oriented to fabrication and characterization a graphene-based photodetector device. The last scientific objective of the project is dedicated to the integration of hafnium oxide thin films as scintillator elements and G-FET devices as photodetector in one X-ray sensor concept. Detecting weak signal within short response time is crucial in applications such as X-ray imaging systems.

Objective 1: Evaluation of the X-ray luminescence properties of hafnium oxide thin films
Experimental investigation of the X-ray-induced luminescence capabilities of hafnium oxide (HfO₂) thin films, with thicknesses ranging from 10 to 100 nm, deposited by Atomic Layer Deposition (ALD).

Objective 2: Development of a graphene-based photodetector (G-FET)
This objective aims to develop a graphene-based photodetector with a field-effect transistor (FET) configuration, referred to as G-FET. The device will exploit the exceptional properties of graphene, such as its high electron mobility and rapid photoresponse, to enable sensitive and precise photoelectric detection.

Objective 3: Integration of hafnium oxide films and G-FET devices for X-ray sensors
This objective focuses on integrating hafnium oxide thin films, used as scintillating elements, with G-FET devices acting as photodetectors, into a unified planar sensor concept for X-ray detection. By combining these two complementary functional components, the goal is to develop a compact and efficient system capable of converting X-ray radiation into precisely detectable electrical signals.

• 3 papers published in ISI-indexed journals, with at least 2 published as Open Access (OA);
• 2 papers presented at national or international conferences;
• 1 patent application for the developed technology;
• 1 innovative concept for an X-ray sensor.