We have measured the resonant tunneling current–voltageI(V) characteristics of strainedp‐Si/Si1−xGexdouble‐barrier microstructures ranging from 1.0 to 0.1 &mgr;m in lateral extent. The bias spacing between resonant current peaks in theI(V) reflects the energy separation of the Si1−xGexquantum well subbands, which is partially determined by the strain. As the lateral size of the structures decreases, we observe consistent shifts in theI(V) peak spacing corresponding to strain energy relaxation of ∼30% in smaller structures. An additionalI(V) fine structure is observed in the 0.1 &mgr;m device, consistent with lateral quantization due to nonuniform strain. ©1995 American Institute of Physics.