Improved External Quantum Efficiency of GaN p-i-n Photodiodes With a TiO$_{2}$ Roughened Surface

Gallium nitride p-i-n ultraviolet photodiodes (PDs) with a titanium dioxide (TiO
₂
) nano-particles roughened surface have been fabricated. It was found that the responsivity and external quantum efficiency can be improved 60% on the surface roughened PDs. It was also found that light absorption can be enhanced from various incident angles by the TiO
₂
roughened surface. Furthermore, the high detectivity of 9.2 times 10
¹³
cmldrHz
<sup>1

/2</sup>
ldrW
^-1
can be achieved from the PD with a rough surface.