Growing Al2O3by Ultrasonic Spray Pyrolysis for Al2O3/AlGaN/GaN Metal-Insulator-Semiconductor Ultraviolet Photodetectors

Abstract

This paper proposed Al 2 O 3 deposition by ultrasonic spray pyrolysis (USP) method as an insulator layer for Al 2 O 3 /AlGaN/GaN metal-insulator-semiconductor ultraviolet photodetector (MIS-UV-PD) applications. The composition of USP-grown Al 2 O 3 was confirmed by X-ray photoelectron spectroscopy. The refractive index and transmittance characteristics of USP-grown Al 2 O 3 were also characterized. The Al 2 O 3 /AlGaN/GaN MIS-UV-PD performances with different Al 2 O 3 thickness (30, 20, and 15 nm) were investigated. The responsivity was 1.3 × 10 -3 /7.5 × 10 -3 /0.83 A/W, UV-to-visible rejection ratio was 2.34 × 10 3 /1.37 × 10 4 /3.18 × 10 5 , and the detectivity was 2.78 × 10 8 /1.26 × 10 9 /1.17 × 10 11 cmHz 0.5 W -1 for the MIS-UV-PD with 30-/20-/15-nm-thick Al 2 O 3 . It was found that the performances of MIS-UV-PD with 15-nm Al 2 O 3 as the insulator layer are much better than the MIS-UV-PD with 20and 30-nm Al 2 O 3 .