Magnetotransport measurements of a SiGe heterostructure containing a 20 nm p-Ge quantum well with a mobility of 800 000 cm2 V-1 s-1. By dry etching arrays of wires with widths between 1.0 microns and 3.0 microns, we were able to measure the lateral depletion thickness, built-in potential, and the phase coherence length of the quantum well.