Diode Characteristics Approaching Bulk Limits in GaAs Nanowire Array Photodetectors.
We present the electrical properties of p-n junction photodetectors comprised of vertically oriented p-GaAs nanowire arrays on the n-GaAs substrate. We measure an ideality factor as low as n = 1.0 and a rectification ratio >108across all devices, with some >109, comparable to the best GaAs thin film photodetectors. An analysis of the Arrhenius plot of the saturation current yields an activation energy of 690 meV-approximately half the bandgap of GaAs-indicating generation-recombination current from midgap states is the primary contributor to the leakage current at low bias. Using fully three-dimensional electrical simulations, we explain the lack of a recombination current dominated regime at low forward bias, as well as some of the issues related to analysis of the capacitance-voltage characteristics of nanowire devices. This work demonstrates that, through proper design and fabrication, nanowire-based devices can perform as well as their bulk device counterparts.
Alan C
0000-0001-6083-9121
AC
Farrell
Pradeep
P
Senanayake
School of Physics and Astronomy, Cardiff University , Cardiff, Wales, United Kingdom.
Xiao
0000-0002-7061-9840
X
Meng
Nick Y
NY
Hsieh
School of Physics and Astronomy, Cardiff University , Cardiff, Wales, United Kingdom.
Diana L
DL
Huffaker
GaAs; Nanowires; photodetectors; surface passivation