Optoelectronic device comprising a semiconductor layer based on GeSn having a single-crystal portion with a direct band structure and an underlying barrier region

An optoelectronic device for emitting or for receiving an infrared radiation, comprising:

• a nucleation layer;
• a crystalline semiconductor layer comprising GeSn, extending in a main plane, having an upper face opposite to the nucleation layer, and comprising:
• a base portion, extending over and in contact with the nucleation layer;
• an upper portion, extending over the base portion, a single-crystal, and under a tensile stress with an average value Cps in the main plane of the crystalline semiconductor layer, composed of a homogeneous medium having a uniform value xps1 of an atomic proportion of tin of the homogeneous medium, the average value εps of the tensile stresses and the uniform value xps1 of the atomic proportion of tin being such that the upper portion has a direct bandgap structure;
• a pin semiconductor junction, comprising a doped region of an n type and a doped region of a p type, flush with the upper face, and an intrinsic region situated within the upper portion and extending between the doped regions;
• and
• metal polarizing contacts, situated on and in contact with the doped regions,
• wherein the single-crystal of the upper portion comprises, aside from the homogeneous medium, vertical structures extending in the homogeneous medium along an axis orthogonal to the main plane over a whole thickness of the upper portion, and having an average value xps2 of the atomic proportion of tin greater than the uniform value xps1, thus forming regions for emitting or for receiving said infrared radiation, and
• wherein the crystalline semiconductor layer furthermore comprises an intermediate portion, situated between and in contact with the base portion and the upper portion along an axis orthogonal to the main plane, the single-crystal of the upper portion, and a region extending in the main plane over its whole width and having an average value xpi1 of the atomic proportion of tin less than the uniform value xps1, thus forming a barrier region against charge carriers flowing in the upper portion.