HIGH GE CONTENT SI/SIGE HETEROSTRUCTURES FOR MICROELECTRONICS AND OPTOELECTRONICS PURPOSES

摘要

SiGe virtual substrates grown by RP-CVD onto Si(001) substrates are characterized by a macroscopic degree of strain relaxation R = 97.2 ± 1.2%, threading dislocations densities as low as 4x10~5 cm~(-2) and rather smooth surfaces (rms roughness : 2 - 5 nm). Such virtual substrates have been used as templates for the formation of SiGe-On-Insulator structures (on which we have studied the specifics of Si and SiGe re-epitaxy). We have also grown Ge thick layers directly onto Si(001). Tensile-strained (R = 107%), smooth (rms ～ 1 nm) Ge layers with a low threading dislocation density (6x10~6 cm~(-2)) are obtained that are characterized by high absorption coefficients : A = 10000 cm~(-1) @ 1.3 μm and 4500 cm~(-1) @ 1.55μm. Finally, we have obtained dense, narrowly size-distributed Ge islands that, when integrated into {Ge quantum dots / Si spacer} stacks, emit light at 1520 nm (PL @ 10K) and are characterized by A ～ 70 cm~(-1) in-between 1.2 and 1.7 μm.