Effect of embedding of CrSi2 and β-FeSi2 nanocrystals into n-type conductivity silicon on the transport and thermal generation of carriers

The possibility of ordered embedding of CrSi2 and beta-FeSi2 nanocrystals (NCs) into a Si(111) substrate of n-type conductivity has been demonstrated. The types of NCs and silicon matching were determined, and the types of the crystal lattice deformations of CrSi2 and beta-FeSi2 NCs were established. For six-layer heterostructures with embedded CrSi2 and CrSi2 + beta-FeSi2 NCs, a change in the Seebeck coefficient sign from negative to positive was observed for the first time in a 250-400 K temperature range, which indicates a nanocrystals to silicon hole injection. An estimate was made of the minimum number of holes, injected from a single nanocrystal, which are necessary to compensate for the thermo-emf from an n-type substrate. Band diagrams were constructed for the beta-FeSi2-p NC/Si-n and CrSi2-p NC/Si-n heterojunctions, and the discontinuities in the valence and conduction bands were determined. The minimum barrier (0.065 eV) for holes in the Si-p/NC beta-FeSi2-p/Si-n system indicates their thermal generation as the main mechanism. The main mechanism of hole injection from Si-p/NC CrSi2-p/Si-n system is tunneling through the surface states in the Si band gap due to the large discontinuity (1.075 eV) in the Si valence band.

Automated summary

Ordered embedding of CrSi2 and β-FeSi2 nanocrystals into an n-type Si(111) substrate has been demonstrated, leading to a change in Seebeck coefficient sign and determination of hole injection mechanisms.