AlGaN Photodetectors Prepared on Si Substrates

AlGaN ultraviolet (UV) metal-semiconductor-metal (MSM) photodetectors (PDs) grown on silicon substrates were fabricated and characterized. With 5-V applied bias, it was found that dark current density of Al
_0.2
Ga
_0.7
N PDs on silicon substrate was only 7.5times10
^-9
A/cm
²
. With an applied bias of 7 V, it was found that peak responsivities were 0.09 and 0.11 A/W while UV/visible rejection ratios (i.e., peak wavelength: 420 nm) were 324 and 278 for Al
_0.2
Ga
_0.8
N and Al
_0.3
Ga
_0.7
N MSM PDs, respectively. Moreover, the noise equivalent power of Al
_0.2
Ga
_0.8
N MSM PDs was estimated to be 3.5times10
^-12
W