Solar Blind Avalanche Photodetector Based on a N-Β-ga2o3/n-si Heterojunction Via an Introduction of AlN Buffer Layer for Interface Lattice and Band Engineering

The ultrawide-band gap semiconductor Ga2O3 as a photodetector heteroepitaxially grown on Si is expected to be widely used for weak solar-blind signal detections because the optical filters typically used in Si-based UV detectors can be avoided. Photodetectors fabricated from Ga2O3/Si are promising for multi-color detection (Ga2O3-based for UV and Si-based for visible/IR) and are more compatible with traditional Si-based electronic circuits. This paper proposes an n-type semiconductor-barrier-n-type semiconductor (n/B/n) with a unipolar barrier β-Ga2O3/AlN/n-Si heterostructure as a solar-blind avalanche photodetector. Introducing the AlN buffer layer eliminates the native amorphous SiOx layer, reduces lattice mismatch between β-Ga2O3 and Si, and improves the quality of β-Ga2O3 crystallization. Embedding AlN increases the conduction band shift of β-Ga2O3/Si, limits electron migration, reduces device dark current, and increases the reverse breakdown voltage. The β-Ga2O3/AlN (150 nm)/n-Si heterostructure has a high responsivity of 131.3 A/W with a detectivity of 2.9 × 1015 Jones, and an ultrahigh UV/visible (Rpeak/R400nm) rejection ratio of 5.2 × 105 at −55 V. The avalanche gain can also reach 2.7 × 104 at an 85 V reverse bias. This work provides an effective strategy for constructing a high-performance avalanche solar-blind-UV/visible/IR as a multi-color photodetector on one “chip” of a Si-based integrated circuit.