  We engineer planar Ge/SiGe heterostructures for low disorder and quiet hole
quantum dot operation by positioning the strained Ge channel 55~nm below the
semiconductor/dielectric interface. In heterostructure field effect
transistors, we measure a percolation density for two-dimensional hole
transport of $2.1\times10^{10}~\text{cm}^{-2}$, indicative of a very low
disorder potential landscape experienced by holes in the buried Ge channel.
These Ge heterostructures support quiet operation of hole quantum dots and we
measure charge noise levels that are below the detection limit
$\sqrt{S_\text{E}}=0.2~\mu \text{eV}/\sqrt{\text{Hz}}$ at 1 Hz. These results
establish planar Ge as a promising platform for scaled two-dimensional spin
qubit arrays.
