PhD thesis 2026-2029 at CEA/Leti and LTM Grenoble

PhD thesis 2026-2029 at CEA/Leti & LTM Grenoble

Advanced chemical characterization of complex III-V heterostructures for optoelectronic and radiofrequency applications using FIB-ToF-SIMS and HAXPES

Keywords: III-V semiconductors, photodetectors, lasers, HBT (heterojunction bipolar transistor), FIB-ToF-SIMS, SIMS, HAXPES

Context of the PhD:

Heterostructures based on III-V semiconductors are nowadays used in many devices for radiofrequency applications, power electronics and optoelectronics. Materials such as arsenides (InGaAs, GaAsSb) and phosphides (InP) are known for their unique optical (direct bandgap) and electronic (high carrier mobilities) properties. Complex heterostructures are thus being developped for infrared detectors and for heterojunction bipolar transistors (HBT) designed for futur 6G wireless communication systems. They rely on complex stacks of ultra-thin layers (a few nm thick) engineered to achieve appropriate band alignment and enable optimal electron transport.

The quality of these devices requires a good control of their structural and chemical properties. The epitaxial growth processes must ensure high crystalline quality, a precise chemical composition with sharp interfaces and controlled doping levels in order to guarantee good devices electrical performances. The main challenge is to reduce element segregation or redistribution phenomena, in order to achieve abrupt interfaces. Another crucial point is to achieve a good control of dopants incorporation to reach high and reproducible doping levels. 

For this purpose, advanced characterization techniques are required in particular to investigate the chemistry of such heterostructures. The thesis work will focus on the development of characterization methodologies for a complete 3D chemical analysis. This research will rely on the complementary expertise of LTM-CNRS in MOCVD growth processes and the expertise of CEA-Leti in materials characterization. 

more information in the pdf document below.