• Cristina Besleaga
• Andrei Nitescu
• Liliana Marinela Balescu
• George Stan
• Andra Georgia Boni
• Mihaela Botea
• Andrei Tomulescu
• Andrei Cristian Kuncser
• Florentina Neatu

GENERAL OBJECTIVE: Fabrication of HZO and AlN thin films using ALD and CVD technologies, followed by their application in field effect transistors and pyroelectric sensors.

SPECIFIC OBJECTIVES:

O1. Obtaining HZO thin films by ALD method and the investigation of their physical properties; degree of completion: 100 %.

HZO films were obtained by the ALD method. The impact of the variation of all process parameters on the structural, morphological, optical and electrical characteristics was tested.
The obtained layers were integrated in capacitor / MIS type structures.
The pyroelectric character of HfO2 -based films was highlighted.

O2. Obtaining AlN thin films by CVD method and the investigation of their physical properties; degree of completion: 100 %.

AlN films were obtained by the CVD method. The obtained layers were characterized structurally, morphologically, optically and electrically.
The manufactured films were integrated in pyroelectric sensors that were tested at different temperatures.

O3. Fabrication of HZO/AlN multilayer devices and their functional characterization; degree of completion: 100 %.

Electronic devices based on AlN/HZO multilayer were fabricated and characterized.

• In the stage I, the first preliminary tests were performed to obtain thin layers of HfO2 by the ALD method.
• In the stage II of the project, the procedures for obtaining HZO and AlN thin films through ALD and CVD were developed.
  The successful use of ALD and CVD techniques for the deposition of these materials represents an important evolution in the field of materials science, at regional and national level. These techniques are underdeveloped in Romania, even though they have demonstrated the extraordinary advantages of development and applicability for large-scale production in the USA and Western Europe.
• In the stage III of the project, the electronic devices based on AlN/HZO multilayer were fabricated and characterized.

Thin films were obtained by ALD or CVD using AnnealSys MC-050 equipment:

HfO2 films crystallized predominantly in the monoclinic phase, but the presence of the orthorhombic crystalline phase was was highlighted by XRD and SAED analyzes. The obtained films are pyroelectric. Moreover, the Capacitance-Voltage measurements indicated that some of HfO2-based materials have semiconductor properties.

The AlN films, deposited by CVD, have a hexagonal polycrystalline structure. They have a dielectric constant of ~ 12 and a breakthrough field greater than 12 MV/cm. The thin layers of AlN have been successfully integrated into pyrotechnic sensors that have been tested at various operating temperatures.

For HZO films, Tetrakis(ethylmethylamido)hafnium(IV) si Tetrakis(ethylmethylamido)zirconium (IV) liquid precursors were used.

For AlN films, Tris(dimethylamido)aluminum(III) and NH3 precursors were used.

The obtained films were investigated using the following equipment (methods): Rigaku SmartLab X-ray (XRD), JEM-ARM200F (JEOL) –HRTEM (TEM si SAED), J.A. Woollam Ellipsometer (optic), Keithley 4200 Semiconductor Analyzer, HP 4194A Impedance Analyzer (electrice), Jasco 6800-FV-BB (FTIR), Horiba LabRAM HR Evolution (Raman), NT-MDT SPM (AFM).

• Dissemination

1. Conferences: Two participations at international conferences; degree of completion: 100 %.

i) The paper entitled “HfO2 / AlN multilayer devices and their functional characterization” was presented online, authors: Andrei Nitescu, Cristina Besleaga, Georgia Andra Boni, Lucian Pintilie, at the ICPAM-13 International Conference, an event that took place in Sant Feliu de Guixols, Spain, 24 - 30 September.

ii) The paper entitled “HfO2 / AlN multilayer devices and their functional characterization” was presented, authors: Cristina Besleaga, Andrei Nitescu, Georgia Andra Boni, Mihaela Botea, Cristian Radu, Lucian Pintilie, at the IBWAP-20 International Conference, an event that took place in Constanta, Romania, 12 - 15 September.

1. Articles: two articles which will be submitted for evaluation to Web of Science® indexed journals, with high impact factor (Q1 quartiles); degree of completion: 100 %..

i) „The impact of aluminum nitride interlayer on the structural and electrical properties of pure hafnia”, autori: C. Besleaga (corespondent), M. Botea, C.M. Istrate, A. Nitescu, G.E. Stan, A.G. Boni, L. Pintilie – article submitted to Advanced Materials Technologies (Q 1 journal – Materials Science, Multidisciplinary category, with an influence score of 1.586 and impact factor of 8.856).

ii) „Fourier-transform infrared spectroscopy as a complementary method for phase identification in hafnia-based materials”, autori: C. Besleaga (corespondent), A. Kuncser, C.C. Negrila, A. Nitescu, G.E. Stan – article submitted to Applied Surface Science (Q 1 journal – Physics, Applied-science si Materials Science, Coatings&Film Science categories, with an influence score of 0.848 and impact factor of 7.392).

1. Patent

A patent application was sent for evaluation: "Method for increasing the performance of pyroelectric devices based on hafnium dioxide", authors: Cristina Besleagă Stan, Mihaela Botea, George Stan, Lucian Pintilie; application number A/00736.

i) „The impact of aluminum nitride interlayer on the structural and electrical properties of pure hafnia”, autori: C. Besleaga (corespondent), M. Botea, C.M. Istrate, A. Nitescu, G.E. Stan, A.G. Boni, L. Pintilie – article submitted to Advanced Materials Technologies.

ii) „Fourier-transform infrared spectroscopy as a complementary method for phase identification in hafnia-based materials”, autori: C. Besleaga (corespondent), A. Kuncser, C.C. Negrila, A. Nitescu, G.E. Stan – article submitted to Applied Surface Science.