Applied Physics Letters · 1984 · 302 citations · 14 references
EngineeringMaterials EngineeringMaterials ScienceElectronic MaterialsSemiconductor DevicesSemiconductor MaterialsDopingSemiconductor Device MaterialsSemiconductor HeterostructuresSemiconductor PhysicsStrain EngineeringTwo-dimensional SemiconductorsCharge Carrier DensityHeterojunctionsHeterostructuresModulation DopingMolecular Beam EpitaxyStrain EffectsStrained-layer HeterostructuresTemperature Dependence
We report the first observation of the modulation doping effect in Si/Ge0.2Si0.8 heterojunctions grown by molecular beam epitaxy. Peak hole mobilities of ∼3300 cm2 V−1 s−1 have been observed at 4.2 K. These values, although nonoptimum, are comparable to the best reported values for holes in Si/SiO2 inversion layers. Low temperature, angular dependent, Shubnikov–de Haas measurements have demonstrated the two-dimensional nature of the hole gas and yield a surface carrier density of 3.5×1011 cm−2. From the temperature dependence of the Shubnikov–de Haas amplitudes a hole effective mass of 0.30±0.02mo has been derived. Identical measurements on n-type heterojunctions having the same Ge content (x=0.2) have failed to show a sustained enhancement of mobility at low temperatures, indicating that ΔEv≫ΔEc.
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Electron mobilities in modulation-doped semiconductor heterojunction superlattices
R. Dingle, H. L. Störmer, A. C. Gossard et al. · Applied Physics Letters · 1978 · 1.5K citations
Intrinsic Optical Absorption in Germanium-Silicon Alloys
R. Braunstein, A. R. Moore, Frank Herman · Physical Review · 1958 · 674 citations