Method for fabricating a heterostructure comprising active or passive elementary structure made of III-V material on the surface of a silicon-based substrate

A process for fabricating a heterostructure comprising at least one active photonic elementary structure made of III-V material on a surface of a silicon-based substrate, the process comprising:

• producing a first pattern having at least one first opening having a first width and a first height in a first dielectric material on the surface of a first silicon-based substrate, wherein the first height is more than 1.4 times the first width, and wherein producing the first pattern comprises:
• producing a layer of the first dielectric material covering an entirety of the surface of the first silicon-based substrate;
• producing the at least one first opening in the layer of the first dielectric material, the at least one first opening comprising at least one primary opening having one lower vertical portion and one upper horizontal portion, said lower vertical portion being off-center with respect to said upper horizontal portion;
• producing at least one elementary base layer made of III-V material comprising a lower vertical portion and a horizontal portion, wherein the at least one elementary base layer is produced by performing a first operation for epitaxy of the III-V material;
• and
• producing said active photonic elementary structure on a surface of the horizontal portion of said at least one elementary base layer made of III-V material, off-center with respect to the lower vertical portion of said at least one elementary base layer made of III-V material;
• after performing the first operation for epitaxy, producing a second pattern in a second dielectric material so as to define at least one second opening having an overlap with said at least one elementary base layer made of III-V material;
• a second operation for epitaxy of at least one III-V material on the surface of the horizontal portion of said at least one elementary base layer made of III-V material so as to produce said at least one elementary structure made of III-V material(s) in said at least one second opening, said at least one elementary structure having an outer face;
• an operation for transferring and assembling said at least one elementary structure via its outer face, on an interface that comprises passive elements and/or active elements, said interface being produced on a surface of a second silicon-based substrate;
• and
• removing the entirety of said first silicon-based substrate and of said at least one elementary base layer made of III-V material located on said at least one elementary structure,
• wherein said at least one elementary base layer made of III-V material in said at least one first opening is configured so that growing defects of the heterostructure are confined in said at least one elementary base layer.