(a) Calculated carrier mobilities and (b) band gap energy of (100) Ge as function of biaxial tensile strain (Figures reproduced from Ref. 10).
Ge band structure (a) without and (b) with biaxial tensile strain.
Reflectivity of wafer surface recorded by EpiTT as a function of growth time for a growth of Ge on GaAs at ; , GeH4 turned on; , incubation period; , first peak of constructive interference; , second peak of constructive interference; , GeH4 turned off.
AFM images of Ge initiation layers grown on (100) GaAs surface with low Ga-to-As ratio (sample a) and high Ga-to-As ratio (samples b and c).
XTEM images of Ge initiation layers grown on (100) GaAs surface with low Ga-to-As ratio (sample a) and high Ga-to-As ratio (sample c).
Wafer surface reflectivity recorded by EpiTT as a function of growth time. (1) Surface annealed at , Ge growth at . (2) TMGa flowed at , Ge growth at . (3) TMGa flowed at , Ge growth at . Line 1 indicates the shortest initiation time.
AFM images of Ge grown at on (100) GaAs substrate with offcut toward , using optimum surface preparation for Ge initiation.
XTEM images showing Ge growth blocked by defects on surface generated from annealing at .
XTEM images of tensile-strained Ge layers grown on with different In contents: (a) 5%, (b) 11%, and (c) 21%.
(a) AFM images of Ge grown on , same sample as in Fig. 8(c). Nucleation of tensile Ge QDs occurs at the step bunches on . (b) AFM images of an GB surface revealing the step bunches.
Room temperature Raman spectrum of bulk Ge (blue, peak at ), Ge thin film grown on (green, peak at ), and Ge QDs grown on (red, peak at ). For the Ge QDs grown on , the spectrum consists of both an peak (purple dotted line) and a strained Ge (pink dotted line) due to incomplete surface coverage by tensile strain Ge QDs.
Comparison of strain levels measured by Raman spectroscopy in tensile-strained Ge layers and the theoretical lattice mismatch between Ge and .
Comparison of carrier mobilities in tensile-strained Ge with other semiconductors under consideration for high speed CMOS channels.
Process variants of different surface preparation techniques to initiate Ge on GaAs (100) surface.
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