posted on 2019-08-06, 17:45authored byJun Yang, Linlong Tang, Wei Luo, Jun Shen, Dahua Zhou, Shuanglong Feng, Xingzhan Wei, Haofei Shi
Hybrid
graphene/silicon heterojunctions have been widely utilized
in photodetectors because of their unique characteristics of high
sensitivity, fast response, and CMOS compatibility. However, the photoresponse
is restricted by the high reflectance of planar silicon (up to 50%).
Herein, an improved graphene/Si detector with excellent light absorption
performance is proposed and demonstrated by directly growing graphene
on the surface of silicon nanoholes (SiNHs). It is shown that the
combination of SiNHs with conformal graphene provides superior interfaces
for efficient light trapping and transport of the photoexcited carriers.
A high absorption of up to 90% was achieved, and the conformal graphene/SiNH-based
photodetectors exhibited a higher photoresponsivity (2720 A/W) and
faster response (∼6.2 μs), compared with the counterpart
of the planar graphene/Si, for which the corresponding values are
850 A/W and 51.3 μs. These results showcase the vital role of
the material morphology in optoelectronic conversion and pave the
way to explore novel high-performance heterojunction photodetectors.