High-performance solar-blind photodetector of β-Ga2O3 grown on sapphire with embedding an ultra-thin AlN buffer layer.

The authors reported the MOCVD growth of high-quality β-Ga 2 O 3 on c-plane sapphire substrate, resulting in the achievement of high performance solar blind deep UV photodetectors by introducing an ultra-thin AlN buffer seed layer (BSL). Compared with the direct growth of Ga 2 O 3 on the sapphire, the oxygen vacancy of β-Ga 2 O 3 is reduced after introducing an AlN BSL and the full width at half maximum (FWHM) of (-201) diffraction peak becomes narrower. The dark current is reduced by 1000 times and from 10−10 A down to 10−13 A for the metal-semiconductor-metal planner photodetector of β-Ga 2 O 3 thin film with the AlN BSL. And the detectivity reaches 4.65×1015 cm·Hz1/2·W at 5 V bias. This improvement in performance is derived from the improvement of the growth quality of β-Ga 2 O 3 mediated by the AlN BSL due to the decrease of lattice mismatch. The defects in β-Ga 2 O 3 are reduced, the carrier concentration is reduced, the Fermi level is shifted, the depletion region is widened, the probability of electron tunneling in the dark state is reduced, and the dark current is effectively reduced. • Through introduce of AlN buffer seed layer, reduces the lattice mismatch between the sapphire and β-Ga 2 O 3 , and improves the quality of β-Ga 2 O 3. • The β-Ga2O3 thin film photodetector has a low dark current, which is mainly due to the high crystal quality, reduces the intrinsic carrier concentration and broadens the width of the metal-semiconductor interface depletion region. • The high responsivity of the β-Ga 2 O 3 -based photodetector indicates that it is an effective way to optimize the performance of β-Ga 2 O 3 -based devices by lattice engineering. [ABSTRACT FROM AUTHOR]