09 décembre 2022
10h
Louvain-la-Neuve
Auditoire BARB 21, Place Sainte Barbe - will also take place in the form of a video conference
Fabrication and Characterization of Opto-electronic Devices Based on P-type Thin-film Semiconductors by Xi ZENG
Pour l’obtention du grade académique de Doctorat en sciences de l’ingénieur et technologie
In order to achieve large-area photodetection over a few cm2 with higher sensitivity, higher opto-electronic transfer efficiency and lower cost, two p-type thin-film semiconductors, CIGS and CuO, are investigated in this thesis to realize high-performing large-area opto-electronic devices based on the investigations of novel fabrication processes, device designs, characterization and simulation results.
CIGS photodiodes are optimized firstly by reducing the CIGS thickness below 1 mm, introducing industry-compatible flexible steel substrates, alkali doping and multiple buffer layers (CdS and Cd-free In2S3). Dual-mode photodetection of CIGS photodiodes are fully characterized for the first time both in the photovoltaic and photoconductive modes. In addition, a corrected photoconductive gain mechanism is firstly investigated to accurately explain the operation mechanisms of CIGS photodiodes.
As a more sustainable semiconductor material than CIGS, full fabrication and characterization of large-area CuO thin films and related devices with excellent performances require further investigation. Targeting the best-performing p-type CuO with bandgap around 1.5 to 1.7 eV, carrier concentration around 1015 cm-3, absorption coefficient over 105 cm-1, and maximum carrier mobility, magnetron sputtering is introduced as a reliable technique in large-area fabrication. To investigate the interfacial properties of CuO with metal and dielectric, the Au/CuO transmission line model (TLM) and the CuO metal-oxide-semiconductor (MOS) capacitor are studied. Finally, TFTs with HfO2 gate dielectric are fabricated, characterized, and analyzed on soda lime glass.
Jury members :
- Prof. Denis Flandre (UCLouvain), supervisor
- Prof. Christophe Craeye (UCLouvain), chaiperson
- Dr. Nicolas André (UCLouvain), secretary
- Prof. Laurent A. Francis (UCLouvain)
- Prof. Lei Liao (Hunan University, China)
- Prof. Guoli Li (Hunan University, China)
- Prof. Benjamin Iniguez (Universitat Rovira i Virgili, Spain)
Pay attention :
The public defense of Xi Zeng scheduled for Friday 09 December at 10:00 a.m. will also take place in the form of a video conference