In this work, a p-n junction-coupled metal-insulator-semiconductor (MIS) normally-off high-electron-mobility transistor (HEMT) UVPD is proposed. A two-dimensional electron gas (2DEG) at the AlN/U-GaN interface is entirely depleted with a dark current of 1.97 × 10−11 A because of the design of the sandwiched p-GaN layers. Under 365 nm illumination, the 2DEG is light triggered at Vds = 1 V with a high light on/off ratio of over 107 at a light power density of 286.39 mW·cm−2. Meanwhile, it exhibits fast rise and decay times of 248.39 and 584.79 µs, respectively. Moreover, a maximum responsivity (R) of 2.33 A/W, a maximum EQE of 793%, and a D* of 1.08 × 1013 Jones are obtained at Vds = 1 V. This can be attributed to the built-in electric fields in the configuration, which accelerate the flow of photogenerated carriers into the AlN/U-GaN channel. Additionally, the device showcases stable durability, repeatability, and a low driving voltage, making it highly suitable for applications in UV communication and space exploration.
We report an ultraviolet photodetector (UV PD) based
on a gallium
nitride (GaN) metal oxide semiconductor field effect transistor (MOSFET)
with a 5.9 μm thick n–p–n+ heterojunction
grown on a 4 inch sapphire substrate by metal organic chemical vapor
deposition (MOCVD). The UV PD incorporates a trench gate vertical
MOSFET with a high-quality 5 μm thick drift layer, showing enhancement
mode operation with a threshold voltage (V
th) of 7 V and an I
light/I
dark ratio exceeding 106. Benefiting from the
built-in electric fields across the n–p–n junction and
the photoconductive effect, the device shows an extremely low dark
current of 10.5 pA. Additionally, the photodetector demonstrates outstanding
performance with a high responsivity (R) of 151.62
A/W, an external quantum efficiency (EQE) of 5.51 × 104%, and a specific detectivity (D*) of 2.15 ×
1013 Jones at V
ds = 5 V and V
gs = 15 V under 365 nm illumination. Impressively,
a fast response speed of 1.34/4.72 ms is obtained at V
gs = 9 V. The above performance represents a promising
candidate in UV security communications, medical imaging on low-cost
sapphire substrate.
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