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 spatially inhomogeneous strain field within the dot which can induce lateral quantum confinement, in addition to the usual vertical confinement. As a result, a fine structure appears in the resonant tunneling current-voltage $I\left(V\right)\mathrm{}$ characteristics. Here we present the magnetotunneling $I(V,B)\mathrm{}$ characteristics in parallel magnetic field $B\Vert I$ which provide an experimental probe of the hole states confined by the radially symmetric strain-induced potential in the quantum dot. The evolution of the fine structure with B reveals the influence of the magnetic confinement on the resulting one-dimensional ringlike hole subbands, which is consistent with numerical analysis of hole states of the quantum dot in magnetic field.