Effect of B and N isovalent impurities on the electronic transport of GaAs and GaP based alloys for silicon photonics and photovoltaics

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Incorporating isovalent boron or nitrogen into GaAs, GaP and corresponding In-containing alloys is the only way to obtain high-quality monolithic growth of such III-V semiconductors on Si substrates, which is a major step towards silicon photonics, i.e. the integration of III-V optoelectronics and silicon electronics on the same substrate. However, this alloying not only reduces the average lattice constant, essential for obtaining lattice-matching with silicon, but also induces, in the vicinity of the conduction band edges of these alloys, N and B related localized states which act as traps and scattering centers and thus have a negative effect on electron transport. As these alloys will be employed in the n-type contact regions of silicon photonic device structures, the impact of these intrinsic effects needs to be studied and understood in order to successfully prepare silicon photonic devices following this approach. In addition, due to the polarity difference between silicon and III-V, space charges at the interface between the materials, crossdoping, and antiphase boundaries may occur, which not only affect the transport through the interface itself, but also affects extrinsically transport in the B or N containing III-V contact layer above. We propose to perform a comprehensive study of these effects on the electronic transport by performing magnetotransport experiments under hydrostatic pressure up to 1.5 GPa in the temperature range between 1.5 and 300 K as well as vertical transport measurements. Four kind of alloy (e.g. Ga(N,As), (B,Ga)As, Ga(N,P), (B,Ga)P) grown on III-V as well as Si-substrates, which either differ with respect to the conduction band structure of the host or the character of the isovalent impurity, will be studied and compared. State-of-the-art semiconductor samples are provided by external partners. The interpretation of the experimental results will be carried out in close established cooperation with leading theoretical groups in the field.