Radial Junction Silicon Nanowire Photovoltaics With Heterojunction With Intrinsic Thin Layer (HIT) Structure

Single-wire radial p-i-n heterojunction with intrinsic thin layer nanowire solar cell devices were fabricated by plasma-enhanced chemical vapor deposition of thin intrinsic and n-type hydrogenated amorphous silicon (a-Si:H) shell layers on p-type silicon nanowires synthesized by vapor-liquid-solid growth. The thin intrinsic a-Si:H layer provided an effective passivation of the crystalline Si nanowire surface, and the corresponding device exhibits a dark current density of 1.6 × 10
^-7
A/cm
²
. Under one-sun illumination, the device shows a short-circuit current (I
_sc
) of 2.66 × 10
^-7
mA, open-circuit voltage (V
_oc
) of 0.46 V, fill factor (ff) of 0.52, and energy conversion efficiency (η) of 6.3%. Indium tin oxide (ITO) contacts were also deposited on the n-type shell as an antireflection layer to improve light absorption in the nanowire device. After ITO deposition, the device exhibited a larger I
_sc
of 2.75 × 10
^-7
mA, but the overall efficiency decreased due to a larger leakage current and lower V
_oc
.