Producing high quality homogeneous termination layer for III-V wafers to reduce epi-growth defects and improfe wafer bonding processes
It is well known that the availability of epi-ready wafers used without chemical pre-treatment is crucial for the fabrication of reproducible high-quality epitaxial layers grown by MBE or MOVCD.
The substrate wafers are generally cleaned using chemical etching treatments that lead to carbon and native oxide contamination which can hardly be eliminated by in situ thermal annealings before the epi growth.
To overcome this difficulty, after the last chemical cleaning step substrate suppliers grow a thin oxide layer to protect the surface during further handling. The oxide has to be homogeneous in order to protect the surface from contamination and its thickness has to be thinner than 10-12 A in order to be desorbed by heating, under arsenic or phosphorus overpressure, at temperatures which do not deteriorate the substrate.
These steps usually leave surface state defects levels that later on during the epi growth will result in defective areas that will affect the devices.
Kontrox™ creates a very thin crystalline termination oxide layer, approximately 2ML thick. It's very low surface state defect density and stability under air exposure provide reliable protection for the III-V substrates prior to the growth of epitaxial layers. It is also highly effective for III-V wafer bonding processes used in applications such as multijunction cells concentrated photovoltaics, or special substrate applications like III-V-on-insulator stacks.