International audienceCreating 3D micro/nano-structures inside semiconductors, such as Silicon or GaAs, is a key for numerous advanced applications from microelectronics to integrated photonics, micro-electro-mechanical systems (MEMS) manufacturing. Direct ultrafast laser writing introduces a promising alternative to lithographic methods for this purpose because of its capability with focused infrared beams to precisely induce micro/nano-scale structures. This has already been successfully applied in wide bandgap materials, but recent research indicates more severe difficulties for applications in semiconductors [1-3]. The inherent properties of narrow bandgap and large nonlinear refractive index materials lead to strong deteriorations of t...