1 research outputs found
Enhanced Performance of Ge Photodiodes <i>via</i> Monolithic Antireflection Texturing and α‑Ge Self-Passivation by Inverse Metal-Assisted Chemical Etching
Surface
antireflection micro and nanostructures, normally formed
by conventional reactive ion etching, offer advantages in photovoltaic
and optoelectronic applications, including wider spectral wavelength
ranges and acceptance angles. One challenge in incorporating these
structures into devices is that optimal optical properties do not
always translate into electrical performance due to surface damage,
which significantly increases surface recombination. Here, we present
a simple approach for fabricating antireflection structures, with
self-passivated amorphous Ge (α-Ge) surfaces, on single crystalline
Ge (c-Ge) surface using the inverse metal-assisted chemical etching
technology (I-MacEtch). Vertical Schottky Ge photodiodes fabricated
with surface structures involving arrays of pyramids or periodic nano-indentations
show clear improvements not only in responsivity, due to enhanced
optical absorption, but also in dark current. The dark current reduction
is attributed to the Schottky barrier height increase and self-passivation
effect of the i-MacEtch induced α-Ge layer formed on top of
the c-Ge surface. The results demonstrated in this work show that
MacEtch can be a viable technology for advanced light trapping and
surface engineering in Ge and other semiconductor based optoelectronic
devices