  Exploring hit positions of recorded events can help to understand and
suppress backgrounds in rare event searching experiments. In this study, we
virtually segment a small contact P-type high purity germanium detector (HPGe)
into two layers. Single-site events (SSEs) in each layer are selected by an
algorithm based on two pulse shape parameters: the charge pulse drift time
($T_{Q}$) and current pulse rise time ($T_{I}$). To determine the shapes and
volumes of the two layers, a Th-228 source is placed at top and side positions
to irradiate the detector. The double escape peak events from 2614.5 keV
$\gamma$-ray are selected as typical SSEs, their numbers in the two layers are
used to calculate the volumes and shapes of those layers. Considering the
statistical and systematic uncertainties, the inner layer volume is evaluated
to be 47.2\%$\pm$0.26(stat.)\%$\pm$0.22(sys.)\% of the total sensitive volume.
We extend our analysis for SSEs in 1400-2100 keV, the spectra of inner layer
events acquired from experimental data using the selection algorithm are in
good agreement with those from the simulation. For sources outside the HPGe
detector, the outer layer can act as a shielding for the inner layer. Selecting
the inner layer as the analysis volume can reduce the externalbackground in the
signal region of Ge-76 neutrinoless double beta (0$\nu\beta\beta$) decay. We
use the Th-228 source to evaluate the background suppression power of the
virtual segmentation. After performing the single and multi-site event
discrimination, the event rate in the 0$\nu\beta\beta$ signal region can be
further suppressed by 12\% by selecting the inner layer as the analysis volume.
The virtual segmentation could be used to efficiently suppress surface
background like electrons from Ar-42/K-42 decay in 0$\nu\beta\beta$ experiments
using germanium detector immersed in liquid argon.
