  The \textsc{Gerda} experiment searches for the neutrinoless double beta
($0\nu\beta$beta$) decay of $^{76}$Ge using high-purity germanium detectors
made of material enriched in $^{76}$Ge. For Phase II of the experiment a
sensitivity for the half life $T_{1/2}^{0\nu}\,\,\sim2\cdot10^{26}$ yr is
envisioned. Modified Broad Energy Germanium detectors (BEGe) with thick n$^+$
electrodes provide the capability to efficiently identify and reject background
events, while keeping a large acceptance for the $0\nu\beta$beta$-decay signal
through novel pulse-shape discrimination (PSD) techniques.
  The viability of producing thick-window BEGe-type detectors for the
\textsc{Gerda} experiment is demonstrated by testing all the production steps
from the procurement of isotopically modified germanium up to working BEGe
detectors. Comprehensive testing of the spectroscopic as well as PSD
performance of the \textsc{Gerda} Phase II prototype BEGe detectors proved that
the properties of these detectors are identical to those produced previously
from natural germanium material following the standard production line of the
manufacturer.
  Furthermore, the production of BEGe detectors from a limited amount of
isotopically modified germanium served to optimize the production, in order to
maximize the overall detector mass yield. The results of this test campaign
provided direct input for the subsequent production of the enriched germanium
detectors.
