arXiv:2511.20842v1 Announce Type: new
Abstract: Understanding how charge-carrier mobility evolves as high-purity germanium (HPGe) is thinned from bulk to micrometer scale is essential for optimizing advanced radiation detectors, thin-body Ge electronics, and emerging quantum devices. We report, to our knowledge, the first systematic thickness-dependent mobility study on bulk-grown, detector-grade HPGe, performing Hall-effect measurements on $n$- and $p$-type samples thinned from $2.7~mathrm{mm}$ down to $7~mathrm{mu m}$ at room temperature. The mobility follows an extended-exponential dependence $mu(t) = mu_0 left[ 1 – expbig( – (t/tau)^{beta} big) right]$ with characteristic electrostatic lengths $tau = 6$–$50~mathrm{mu m}$. Comparison with boundary-scattering and depletion-based models shows that mobility degradation is dominated not by Fuchs–Sondheimer surface scattering but by electrostatic depletion that reduces the effective conducting channel thickness. Across all samples, the hierarchy $lambda_D