  We demonstrate shadow evaporation-based fabrication of high-quality
ultrasmall normal metal -- insulator -- superconductor tunnel junctions where
the thickness of the superconducting electrode is not limited by the
requirement of small junction size. The junctions are formed between a film of
manganese-doped aluminium acting as the normal conducting electrode, covered by
a thicker, superconducting layer of pure Al. We characterize the junctions by
sub-gap current--voltage measurements and charge pumping measurements in a
gate-driven hybrid single-electron transistor, operated as a turnstile for
single electrons. The technique allows to advance towards turnstiles with close
to ideally thermalized superconducting reservoirs, prerequisite for reaching
metrological current quantization accuracy in a hybrid turnstile. We further
present an alternative way to realize small junctions with thick Al leads based
on multi-angle deposition. The work enables the future investigation of
turnstiles based on superconductors other than Al, and benefits various other
Al tunnel junction devices for which quasiparticle thermalization is essential.
