AlGaN‐Based Solar‐Blind Ultraviolet Detector with a Response Wavelength of 217 nm

The research of the high Al(x = 0.75) component has always been the focus of the AlGaN solar‐blind ultraviolet (UV) detector. However, due to the lattice and thermal mismatch between the AlGaN and the underlying substrate under existing mainstream heteroepitaxial growth methods, the large density of defects, e.g., point defects, screw dislocations, and edge dislocations, has hindered the performances of AlGaN‐based solar‐blind UV photodetectors. A short superlattice polarization‐induced P‐type doping growth technique is used to fabricate a high‐performance AlGaN‐based back‐illuminated solar‐blind UV p‐i‐n photodetector (PD) fabricated on sapphire substrates. The back‐illuminated AlGaN UV‐PD shows a high external quantum efficiency of 70.2%. The peak responsivity (R) reaches 123 mA W−1 at −5 V with a wavelength of 217 nm. Meanwhile, the dark current density is 2.21 × 10−8 A cm−2. Additionally, the UV/visible rejection ratio for the detectors exceeds four orders of magnitude, and the detectivity (D*) is calculated to be 6.7 × 1012 cm Hz1/2 W−1. The device performance parameters can be attributed to the quality of the epilayer and heterojunctions. This technology provides new ideas for nitride semiconductor materials, further bringing a breakthrough in a wide‐bandgap electronics device.