Magnetotunneling spectroscopic probe of quantization due to inhomogeneous strain in a Si/SiGe vertical quantum dot

A columnar p-Si/SiGe quantum dot is etched from a strained layer structure. The creation of the stress-free lateral face of the column results in a sp atially inhomogeneous strain field within the dot which can induce lateral quantum confinement, in addition to the usual vertical confinement. As a re sult, a fine structure appears in the resonant tunneling current-voltage I( V) characteristics. Here we present the magnetotunneling I(V,B) characteris tics in parallel magnetic field B parallel to I which provide an experiment al probe of the hole states confined by the radially symmetric strain-induc ed potential in the quantum dot. The evolution of the fine structure with B reveals the influence of the magnetic confinement on the resulting one-dim ensional ringlike hole subbands, which is consistent with numerical analysi s of hole states of the quantum dot in magnetic field.